There are 48 half-hourly Settlement PeriodsA half-hour slot. A normal day has 48 of them. in a day, and a supplier has to be settled on what its customers used in each one. But a traditional, non-smart meter gives only an occasional reading, not a half-hourly trace. Profiling fills the gap: it takes a customer's annual consumption, applies an average daily shape for their type of customer, scales it for network losses, and reconciles it to the energy actually measured flowing into the region. All of this sits under the Balancing and Settlement Code (BSCBalancing and Settlement Code: the industry rulebook that governs electricity settlement, administered by Elexon.), administered by ElexonThe organisation that administers the Balancing and Settlement Code and runs central settlement..
The guide has two halves. Parts 00–05 explain the current regime, from the codes on a supply point through the profiling engine to the reconciliation clock. Parts 06–09 explain Market-wide Half-Hourly Settlement (MHHSMarket-wide Half-Hourly Settlement: the reform settling every meter half-hourly, using actual half-hourly data wherever a meter provides it.), which replaces the estimation with measurement, compresses the settlement timetable from 14 months to four, and is mid-migration as you read this. In short: the current regime estimates the shape of a customer's use, spreading their yearly total across the day using standard consumption patterns, while MHHS measures how much was actually used in each half hour. Almost every other difference between the two regimes follows from that.
How Great Britain settles electricity today, for the supply points that haven't yet migrated: the codes on a supply point, the SSCStandard Settlement Configuration: a code saying how many registers a meter has and which time windows group them./TPRTime Pattern Regime: the switching pattern that says which half hours a particular meter register records in. timetable that carves up the day, the profiling engine that turns a year into 48 half hours, regional pricing, and the reconciliation clock.
Money has to follow energy, half hour by half hour, even when nobody measured it that finely.
Electricity is unlike most things you buy: it can’t be stored at grid scale in any real quantity. So at every moment, the amount being generated has to match the amount being used.1 Great Britain organises this through a wholesale market. Ahead of time, suppliers buy the energy they expect their customers to use, and generators sell the energy they will produce.2 To keep the accounting exact, each day is split into 48 half-hourly Settlement PeriodsA half-hour slot. A normal day has 48 of them. (46 or 50 on the two days a year when the clocks change).2
At the end of each day, someone has to work out what really happened: for every half hour, how much did each supplier’s customers actually use? Pinning down those volumes is what settlement means, and ElexonThe organisation that administers the Balancing and Settlement Code and runs central settlement. runs it centrally under the Balancing and Settlement Code (BSCBalancing and Settlement Code: the industry rulebook that governs electricity settlement, administered by Elexon.).3
Settlement then sets that actual use against what the supplier had contracted to buy. Any gap is charged or paid at the imbalance priceThe price for each half hour at which a supplier's shortfall or surplus is settled, set by the cost of balancing the system.: a price set for each half hour, based on what it cost the system operatorThe organisation that balances supply and demand on the grid in real time; in Great Britain this is NESO. to keep supply and demand balanced in that period. So getting each customer’s half-hourly use right is not just tidy accounting; it is what a supplier’s costs turn on.2
Since 2015 there has been a single imbalance price for each half hour, the same figure whether a supplier fell short and has to buy or ran long and gets paid.2
That price tracks the marginal cost of the actions the system operator took to fix the system’s overall balance. It runs high when the whole system was short, and low, sometimes negative, when it was long.
So it is not a good deal for one side or the other. A supplier gains only when its own imbalance happened to help the system: being long when the system was short is paid that high price. It loses when its imbalance made things worse. The price is also meant to be less attractive than squaring a position in the market ahead of time, so the incentive is always to forecast and contract accurately.
A supply settled half-hourly (HHHalf-Hourly: settled on actual readings for each half-hour period, not on estimates.) produces the half-hourly consumption trace that settlement needs. This could be a larger business site, or a domestic meter that has already migrated to Market-wide Half-Hourly Settlement (MHHSMarket-wide Half-Hourly Settlement: the reform settling every meter half-hourly, using actual half-hourly data wherever a meter provides it.). Many homes and small businesses, however, are still settled non-half-hourly (NHHNon-Half-Hourly: a meter or supply settled on estimates and a profile rather than on actual half-hourly readings.). A traditional meter is read only every few months, or its use is estimated.5 A smart meter does not change that on its own: it can record every half hour, but until its supply point moves to half-hourly settlement, it is settled from its register readings and a standard profile, like any other NHH meter.6
The NHH regime therefore has to estimate two things for each customer: how much electricity they use overall, and how that consumption is distributed across the half hours of the day. Combine them, adjust for losses and regional reality, and you get a half-hourly volume the market can settle. The rest of this guide is how that's actually done.
Every supply point carries a short set of codes that tell settlement what kind of meter it is, how its registers work, where it sits, and which shape to apply. Learn these and the rest falls into place.
The first fork is the Measurement ClassWhether a meter is settled on actual half-hourly readings, or on estimates and a profile. — whether a meter is settled on actual half-hourly readings (HHHalf-Hourly: settled on actual readings for each half-hour period, not on estimates.) or not (NHHNon-Half-Hourly: a meter or supply settled on estimates and a profile rather than on actual half-hourly readings.). Historically, larger sites were HH and the mass of domestic and small-business supplies were NHH and profiled.5 Smart meters blur this line, so it is worth being precise: HH or NHH describes how a supply is settled, not what its meter can record. A smart meter can record every half hour, but under the current regime a smart-metered home is typically still settled as NHH, from register readings and a profile, until its supply point migrates to MHHSMarket-wide Half-Hourly Settlement: the reform settling every meter half-hourly, using actual half-hourly data wherever a meter provides it..6 That migration is now under way (Part 06), and its whole point is to move every supply onto HH settlement.
Every supply point has a Meter Point Administration Number (MPANMeter Point Administration Number: the number that identifies an electricity supply point, printed on bills as a 13-digit core plus a top line of supply details.), printed on bills as two lines.7 The lower line identifies the physical connection; the top line carries codes that settlement cares about. Figure 2A shows the layout used until September 2025, because its three codes are the ones this part explains; Figure 2B, in the note below it, shows today’s layout. Tap each block to see what it means.
The 13-digit bottom line is the MPAN core: a 2-digit Distributor ID, a 10-digit unique number, and a single check digit at the end.9
Does “00” mean a supply has migrated? Not on its own. A migrated supply with no Profile Class shows 00, but migrated two-rate traditional meters keep 02 or 04 on their MPAN under MHHS rules. On a home or small business bill, 00 is a strong sign of migration rather than proof; the supplier can confirm.1012
This is the same home as Figure 2A: a single-rate supply that has not yet migrated to MHHS, so it keeps its Profile Class and shows its Line Loss Factor Id. SSC 0393 is the standard single-rate (Unrestricted) configuration, with one register on TPRTime Pattern Regime: the switching pattern that says which half hours a particular meter register records in. 00001 recording all day.14
Customers are sorted into eight generic Profile Classes, chosen because each represents a large, fairly similar population.15 Classes 1–2 are domestic, 3–8 are non-domestic. The first two digits of the MPAN tell you the class.715
The important point for today is that only Profile Classes 1–4 are still used for active profiling, and only for supplies that have not yet migrated to MHHS. In April 2017, BSCBalancing and Settlement Code: the industry rulebook that governs electricity settlement, administered by Elexon. Modification P272The 2017 change that moved larger meters (Profile Classes 5 to 8) onto half-hourly settlement. ‘Mandatory Half Hourly Settlement for Profile Classes 5–8’ moved Maximum DemandCustomers (Profile Classes 5 to 8) whose meters record peak demand. These have been half-hourly since 2017. customers onto half-hourly settlement. ElexonThe organisation that administers the Balancing and Settlement Code and runs central settlement. subsequently continued updating the Load Profiles for Classes 1–4, but stopped new load research after late 2024 (Part 03). A PC5–8 site that still does not have half-hourly metering therefore has to fall back on historic Load Profiles.1516 So when this guide refers to “the profiling engine”, it is essentially referring to PC1–4: the profile classes that still cover most domestic and small-business supplies that have not yet migrated to MHHS.
Class definitions and load-factor bands: 15 17
Load Factor measures how steady a customer’s demand is: it compares the energy they actually used over a period with the energy they would have used if their busiest half-hour had run flat-out for the whole period, expressed as a percentage. A site that draws power steadily around the clock scores high; one with short, sharp peaks and long quiet spells scores low. That is what separates these four classes, from PC5 (the peakiest) to PC8 (the flattest, closest to round-the-clock running). Because a customer’s pattern drifts over time, BSCP516 has suppliers recalculate it each year and move the customer between classes when it changes. Elexon’s profiling guidance calls this the Peak Load Factor, while the class titles above and BSCP516 shorten it to LF: it is the same figure, and “peak” simply flags that it is measured against the customer’s own peak (maximum) demand.1517
Allocation isn't a free choice — BSCP516The BSC procedure that sets the rules for allocating a Non-Half-Hourly supply point's Profile Class and codes. sets the rules, and the answer turns on four questions about the supply point:17
| Test | What it decides |
|---|---|
| Import or Export? | Whether the metering system (MSIDMetering System Identifier: the reference for the metering system at a supply point.) draws electricity from the grid (import) or feeds it back in (export), such as a generator or solar site. Almost every home and business is import; export supplies run on their own separate configurations. |
| Domestic or non-domestic? | Whether the site is a home or a business. Homes take Profile Classes 1 to 2; non-domestic sites such as shops, offices and industry take Profile Classes 3 to 8. This is the first fork. |
| Switched load capability? | Whether the meter can switch loadA meter that can switch between registers (rates) on a set time pattern, such as a cheaper overnight rate. between rates on a timer. A single-rate meter is UnrestrictedA single-rate setup: one register, no time-switching. (PC1 for homes, PC3 for business); one with a cheaper timed night rate is Economy 7A two-rate tariff with a cheaper seven-hour overnight register. (PC2 for homes, PC4 for business). |
| Is Maximum Demand recorded? | Whether the meter has a Maximum Demand registerA meter register that records the site's highest (peak) demand. Sites with one sit in Profile Classes 5 to 8. logging the site's peak. If it does, the site sits in the load-factor-banded classes PC5 to PC8; and since P272The 2017 change that moved larger meters (Profile Classes 5 to 8) onto half-hourly settlement., these larger sites are settled half-hourly rather than by profile. |
There are sensible defaults for the unknowns. Where a supplier doesn't know whether a non-domestic site has switched load, and MD isn't recorded, BSCP516 directs it to Non-Domestic Unrestricted (PC3) — and all new connections in that position default there too.17
A single number can't capture a two-rate meter, so two more codes describe the register set-up:
| Code | What it does |
|---|---|
| Standard Settlement Configuration (SSCStandard Settlement Configuration: a code saying how many registers a meter has and which time windows group them.) 4 digits | Specifies how many registers the meter has and, via its Time Pattern Regimes, the times each register records.18 |
| Time Pattern Regime (TPRTime Pattern Regime: the switching pattern that says which half hours a particular meter register records in.) 5 digits | A pattern of switching through time that determines when a given Settlement Register is — or isn't — recording.18 |
| Meter Timeswitch Code (MTCMeter Timeswitch Code: a code describing a meter's switching arrangement and payment type.) 3 digits | Describes the metering/switching equipment, and in practice is also used to flag payment type (e.g. credit vs prepayment). It forms valid combinations with SSCs.8 |
Worked example. Start with the simplest case: a single-rate domestic meter. Its SSC has just one register, whose TPR covers every Settlement PeriodA half-hour slot. A normal day has 48 of them., so everything the meter records is settled as a single block across the whole day.
An Economy 7 meter is where the codes start to earn their keep. Its SSC defines two registers, each with its own TPR. One register's TPR marks out the seven cheaper night hours; the other covers the remaining 17. The seven hours are usually a single overnight block, but not always: some configurations split them in two, and the exact times depend on the region and how the meter is configured rather than being set nationally. The meter records energy on whichever register is live at the time, so between them the two registers account for every half hour of the day, with no overlap and no gap:19
Each register is read separately, and settlement profiles each one onto only the half hours its TPR covers. That is how a two-rate tariff becomes two streams of half-hourly volumes.
Great Britain is divided into 14 Grid Supply Point (GSP) Groups — 12 in England & Wales and 2 in Scotland — each a collection of grid supply points for a region.5 The GSP Group matters three times over: profiles are calculated per region (weather and daylight differ), losses differ by region, and the GSP Group is the boundary at which profiled energy gets reconciled to actual metered energy.20 It's also the basis for regional pricing in Part 04.
| ID | Region | Distribution operator (DNO) |
|---|---|---|
| _A | Eastern England | UK Power Networks (EPN) |
| _B | East Midlands | National Grid Electricity Distribution |
| _C | London | UK Power Networks (LPN) |
| _D | Merseyside & North Wales | SP Energy Networks (SP Manweb) |
| _E | West Midlands | National Grid Electricity Distribution |
| _F | North East | Northern Powergrid (Northeast) |
| _G | North West | SP Electricity North West |
| _H | Southern | SSEN (Southern Electric Power Distribution) |
| _J | South East | UK Power Networks (SPN) |
| _K | South Wales | National Grid Electricity Distribution |
| _L | South West | National Grid Electricity Distribution |
| _M | Yorkshire | Northern Powergrid (Yorkshire) |
| _N | Southern Scotland | SP Energy Networks (SP Distribution) |
| _P | Northern Scotland | SSEN (Scottish Hydro Electric Power Distribution) |
SP Electricity North West was renamed from Electricity North West in 2025, after Iberdrola (ScottishPower’s parent) acquired a majority stake in 2024; it remains a separately licensed network from SP Energy Networks.22 The letters skip I and O to avoid confusion with digits.
When a two-rate meter reports 4,000 kWh on its night register, which half hours does that energy belong to? The answer is a small, precise data model.
Part 01 introduced the three codes that travel together (Table 2). It helps to keep their jobs apart: the Profile ClassOne of eight standard customer types (for example, a domestic single-rate home) used to shape estimated demand. gives the shape, the SSCStandard Settlement Configuration: a code saying how many registers a meter has and which time windows group them. says how many registers (buckets) the day is split into, and each TPRTime Pattern Regime: the switching pattern that says which half hours a particular meter register records in. sets the clock windows for one of those buckets. All three are held in Market Domain DataMarket Domain Data: the central reference dataset Elexon publishes, holding the codes and tables everyone settles against.. Put differently, the SSC is the tariff structure and the TPR is the timetable.18
Under the surface, an SSC and its registers are defined by a few linked tables in Market Domain Data. You don’t need the field-level detail to follow the guide, so it sits in the panel below — open it if you want to see exactly how a configuration, its registers and their clock windows are represented.
These aren't abstractions; they are four tables in Market Domain Data.23 The RECRetail Energy Code: the code that, under MHHS, takes over some reference data such as SSCs and TPRs.'s MHHSMarket-wide Half-Hourly Settlement: the reform settling every meter half-hourly, using actual half-hourly data wherever a meter provides it. consequential-change paper sets them out explicitly, because it had to specify which ones survive the move to the Retail Energy Code:24
C for a clock- or timeswitch-driven register and S for one driven by the Radio Teleswitch Service. The GMTGreenwich Mean Time and British Summer Time: whether a time pattern follows clock changes, which affects which half hours a register covers. Indicator settles whether the times below are fixed to GMT year-round or shift with British Summer Time.Every clock interval ultimately resolves to a simple true/false question for each of the 48 Settlement PeriodsA half-hour slot. A normal day has 48 of them.: was this register recording? You can see that pattern directly in the D0018The standard data report that lists, for each half hour, which meter register was recording. Daily Profile Data Report, where the Valid Measurement Requirement flags run as a row of T and F across the half hours.25 Pick a configuration below to see it.
Window times are illustrative of the pattern, not a lookup. Real switching times vary by configuration, distributor and supplier — the authoritative values live in the MDD Clock IntervalThe Market Domain Data record of the exact times, by day of the week, that a time pattern switches on and off. table (Entity 27), viewable through MDD Online on the BSCBalancing and Settlement Code: the industry rulebook that governs electricity settlement, administered by Elexon. Portal.26
For a two-rate meter, settlement also needs a standard way to split one annual estimate between the registers. That split is set by fixed fractions called AFYCsAverage Fraction of Yearly Consumption: the share of a year's use that a profile puts on each register., which differ by region because customers in different areas use their night hours differently.
A two-rate meter gives two readings, so the supplier already knows the split when actual reads are available. But settlement also needs to work from a single estimate — and it needs to seed a brand-new supply point that has no reads at all. That's the job of the Average Fraction of Yearly Consumption (AFYCAverage Fraction of Yearly Consumption: the share of a year's use that a profile puts on each register.): the fraction of annual demand that a given profile allocates to the periods covered by each TPR.27
An AFYC exists for each valid Profile Class / SSC / TPR / GSP GroupGrid Supply Point Group: one of 14 regional areas. Profiles, losses and reconciliation are handled per region. combination. It is what lets an EACEstimated Annual Consumption: an estimate of a customer's yearly use, used before a fresh meter reading. — an Estimated Annual Consumption, the estimate of a customer’s yearly use — be derived and apportioned across the registers. Note the regional dimension — the same Economy 7 configuration carries a different night-register fraction in Northern Scotland than in London527, because the underlying load research says those customers behave differently.
Some two-rate meters used to be switched remotely by a radio signal rather than by their own clock. That Radio Teleswitch ServiceRadio Teleswitch Service: an older system that switched meters between rates using a radio signal. was switched off on 30 June 2026, and the affected customers have moved to smart meters.
Not every multi-rate meter keeps its own time. Two mechanisms exist, and the C/S indicator in Entity 38 tells settlement which is in play:
| Mechanism | How the register switches | Where the times come from |
|---|---|---|
| Clock / timeswitch Indicator C | An internal clock or timeswitch in the meter flips the register at fixed times. | Fixed in MDD — the Clock Interval table. |
| Radio Teleswitch Indicator S | A broadcast radio signal switches the register (and often the heating load itself) remotely. | Not fixed in MDD. The Teleswitch Agent notifies the SVAASupplier Volume Allocation Agent: the central agent that turns profiles into each supplier's half-hourly volumes. of the broadcast switching times for each Teleswitch User and Group on a daily basis.25 |
That daily-notification design was the whole point of RTSRadio Teleswitch Service: an older system that switched meters between rates using a radio signal.: it let a distributor shift when storage heating charged, across a whole group of customers, in response to system conditions. It was in that sense the original demand-flexibility mechanism, running since the 1980s.28
Everything above describes a static clock. A TPR is a fixed timetable, agreed in central reference data, changed through a formal data-change process. It can express "cheap between 00:30 and 07:30", and with multiple intervals it can express something quite elaborate. What it cannot express is a price that changes every half hour, in response to the wholesale market, published a day ahead.
This isn't a matter of opinion. When the industry asked whether dynamic tariffs could be represented by adding new SSCs, RECCoThe company that runs the Retail Energy Code. confirmed that a truly dynamic tariff does not fit the SSC/TPR model at all. The most that could be done is to flag an SSC range as "billed dynamically" — without the codes themselves describing the tariff.24
Use what Parts 01 and 02 have covered to read one real supply point, first in the layout its bills used until September 2025, then in the layout used since.
Take the MPANMeter Point Administration Number: the number that identifies an electricity supply point, printed on bills as a 13-digit core plus a top line of supply details. in Figure 2A, whose top line reads 01 845 110, and read it left to right.
01, the Profile Class. Domestic UnrestrictedA single-rate setup: one register, no time-switching.: a single-rate home, profiled on the PC1 shape.845, the MTCMeter Timeswitch Code: a code describing a meter's switching arrangement and payment type.. The range a code falls in tells you how to read it. Codes 001 to 399 are specific to each distributor, so the same number can mean different things in different areas. Codes 500 to 799 mark related metering systems, where two or more meters at the same premises are billed to one customer. Codes 800 to 999, like this one, are common codes used across the industry.263031110, the LLFCLine Loss Factor Class: the code that sets how much metered use is scaled up for energy lost in the network.. Set by the distributor, it decides which loss factors apply to this supply.In this older layout the SSC is not printed; it is held in the industry data for the supply point. The combination still has to be valid. A Profile Class, MTC, LLFC and SSC only go together in combinations that each distributor has registered, and those valid combinations are listed in Market Domain Data (Entity 63), alongside the switching times (Entity 27).26
On a bill printed today, the same supply point (Figure 2B) reads 01 0393 110.
01, the Profile Class. Unchanged: this home is still profiled on the PC1 shape.0393, the SSC. This is where this part’s codes appear on the bill. SSC 0393 is the standard single-rate configuration: one register, whose TPR (00001) covers all 48 Settlement Periods, so the home’s whole consumption is profiled across the entire day. On an Economy 7 meter this block would instead show a two-register SSC, with one TPR for the night hours and one for the rest of the day.14110, the Line Loss Factor Id. This supply has not yet migrated to MHHS, so the last block still carries its loss-factor code. After migration it would show the DUoS Tariff Id instead, and if the home migrated with a smart meter, the first two blocks could read 00 and 0000 (see the note under Figure 2A).Notice what disappeared: the MTC. It still exists in the industry data for traditional meters, but it is no longer printed on the bill.
One practical lesson that applies to both layouts: two homes can share Profile Class 01 yet sit on different SSC and MTC combinations, for example because they have different makes of meter. They are still profiled on exactly the same shape, because the shape comes from the Profile Class alone. The MDD tables are on MDD Online via the BSC Portal, and a static copy of MDD is planned to be retained for five years after the move to ISDIndustry Standing Data: the MHHS replacement for Market Domain Data, the shared reference data..24
Given only a customer's annual consumption, how is that turned into a half-hourly breakdown across the whole year?
Profiling combines a magnitude (how much, per year) with a shape (what fraction falls in each half hour), then scales and reconciles the result. Here's the chain end to end.
The magnitude is a whole year’s energy in a single number, and it comes in two forms. The Estimated Annual Consumption (EACEstimated Annual Consumption: an estimate of a customer's yearly use, used before a fresh meter reading.) is a forecast of the year’s use, first set when the supply is registered and then refined as actual readings arrive. The Annualised Advance (AAAnnualised Advance: a customer's yearly use recalculated from an actual meter reading.) is the energy actually recorded between two meter readings, expressed as an annual rate. The Non-Half-Hourly Data CollectorThe agent that retrieves meter readings and, for non-half-hourly meters, works out the EAC and AA. calculates both.
For the days between two actual readings, the supplier is settled on the AA; for days not yet covered by a reading, it is settled on the EAC. As fresh readings arrive, later settlement runs swap estimates for actuals.3233
For multi-rate meters, the annual figure must be split between registers. The Average Fraction of Yearly Consumption (AFYCAverage Fraction of Yearly Consumption: the share of a year's use that a profile puts on each register.) is the fraction of annual demand a profile allocates to the periods covered by each TPRTime Pattern Regime: the switching pattern that says which half hours a particular meter register records in. — it's what lets EACs and AAs be derived and apportioned across registers. AFYC values live in the central reference data (Part 05).27
For each class still profiled, the Profile AdministratorProfile Administrator: the agent that builds the load profiles and their regression coefficients. built an average half-hourly shape from a load-research sample of HHHalf-Hourly: settled on actual readings for each half-hour period, not on estimates. meters on real customers. Crucially the shape isn't fixed: it's produced by multi-linear regressionA statistical method that fits a formula to data; here it links half-hourly demand to temperature, sunset time and day of the week. using up to seven variables — temperature, sunset time and day-of-week dummies — so the curve flexes with weather, daylight and weekday/weekend.515
Each day, the Supplier Volume Allocation Agent (SVAASupplier Volume Allocation Agent: the central agent that turns profiles into each supplier's half-hourly volumes.) takes the out-turn temperature (from the Met Office) and sunset data for each GSP GroupGrid Supply Point Group: one of 14 regional areas. Profiles, losses and reconciliation are handled per region.. From these it produces Profile CoefficientsThe estimated fraction of a year's consumption that falls in one Settlement Period.: the estimated fraction of yearly consumption in each Settlement PeriodA half-hour slot. A normal day has 48 of them..1536 Multiply EAC by the coefficient for a half hour and you have that customer's deemed consumption for it. For example, take a home on 3,100 kWh a year. A busy half hour at 6pm on a winter weekday might carry an (illustrative) coefficient of 0.00012 — the profile expects 0.012% of the year’s energy in that period — so its deemed use is 3,100 × 0.00012 ≈ 0.37 kWh. A quiet half hour at 4am, with a coefficient nearer 0.00003, gives about 0.09 kWh. Every period's coefficient across all 365 days sums to 1, so the 17,520 little pieces add back up to the full 3,100 kWh.
The Non-Half-Hourly Data AggregatorThe agent that adds up settled volumes across all of a supplier's meters. sums EAC/AA across all of a supplier's NHHNon-Half-Hourly: a meter or supply settled on estimates and a profile rather than on actual half-hourly readings. meters, grouped by Profile ClassOne of eight standard customer types (for example, a domestic single-rate home) used to shape estimated demand. and configuration within a GSP Group.33 Apply the profile coefficients and you get the supplier's deemed half-hourly demand for the region.
Energy is lost as heat moving through the distribution network, so a supplier must buy more at the grid than its customers receive. Line Loss FactorsThe factor that scales metered use up to cover energy lost in the distribution network. (per Line Loss Factor ClassLine Loss Factor Class: the code that sets how much metered use is scaled up for energy lost in the network., varying by time of day and season) scale consumption up to the volume that entered the network.4
Add up everything suppliers have been allocated in a region for a half hour (half-hourly volumes, profiled volumes and the estimated losses) and the total won't exactly match the GSP Group Take: the energy actually measured entering that region from the transmission system, from neighbouring regions and from local generation. The GSP Group CorrectionA factor, set for every half hour, that scales suppliers' allocated volumes (mainly the estimated ones) so a region's total matches the energy measured entering it. Factor closes that gap, half hour by half hour, so the region balances.520
It is not spread evenly. Scaling weights, set for each category of consumption, decide how much of the correction each category absorbs. Under the current regime it has fallen mainly on the profiled, non-half-hourly volumes, because those are the least certain numbers.37 What it soaks up is anything settlement could not see directly: profiling and estimation errors, inaccurate loss factors, and energy that no registered meter recorded, such as unregistered connections and theft.38 Since MHHSMarket-wide Half-Hourly Settlement: the reform settling every meter half-hourly, using actual half-hourly data wherever a meter provides it. went live in September 2025 the correction has also been applied to half-hourly volumes, with import and export corrected separately.39
The output is the Supplier Purchase MatrixThe output of profiling: the half-hourly volumes each supplier is deemed to have bought in each region, used to settle its imbalance.: the half-hourly volumes each supplier is deemed to have bought, which feed imbalance settlement.40
The regression doesn't just run on temperature; it runs within a defined seasonal and day-type structure. These aren't the meteorological seasons, and there are five of them, not four — including a distinct High Summer to capture the holiday period. The definitions are anchored to clock changes and the August Bank Holiday rather than to calendar dates:15
| Season | Defined as |
|---|---|
| Winter | From the October clock change (BST→GMT) up to and including the day before the March clock change (GMT→BST). |
| Spring | From the March clock change up to and including the Friday before Summer starts. |
| Summer | The ten-week period preceding High Summer, starting on the sixteenth Saturday before the August Bank Holiday. |
| High Summer | Six weeks and two days, from the sixth Saturday before the August Bank Holiday up to and including the Sunday after it. |
| Autumn | From the Monday after the August Bank Holiday up to and including the day before the October clock change. |
Within each season, days are grouped into three day types: Weekdays (WD), Saturdays (SAT) and Sundays (SUN).15 Season and day type together select which regression relationship applies; the day's actual temperature and sunset then flex the curve within it.
A worked read of the default: if a home used electricity perfectly evenly, each half hour would carry 1/48 of the day, about 2.1%. A PC1 home on a winter weekday is far from even. Its busiest half hours fall between about 17:00 and 18:30, and the peak, at 17:30, carries about 3.7% of the day’s energy: over four times the quietest half hour, around 03:30, at about 0.8%. Switch to PC2 and the picture inverts: more than half the day’s energy lands between midnight and 07:30, when the Economy 7 night register is recording.
The Profile Administrator ran a load-research sample: real half-hourly meters on real customers, some Elexon-owned meters fitted in homes and some data supplied by suppliers. The sample was structured as Profile Class → Super Stratum → Stratum so that each class was represented properly rather than by whoever happened to volunteer. Since 2018 it covered only Profile Classes 1 to 4, the classes still being profiled.1534
Suppliers were obliged to recruit customers and provide the data, either by appointing ElexonThe organisation that administers the Balancing and Settlement Code and runs central settlement.'s Data Gatherer and Sample Manager or by using their own agents. BSCP510 governed how that sampling data reached the Profile Administrator.41 That arrangement has now ended: after the BSC Panel’s September 2024 decision, suppliers no longer need to submit sampling data.35
Half-hourly consumption from the sample becomes Group Average Demand (GADGroup Average Demand: the sample's average measured demand in a half hour, used to build profiles.). Repeating that for every half hour of the year gives a 365 × 48 matrix of GADs, which is the dependent variable in the regression.5
The regressions are multi-linear, using up to seven variables — temperature, sunset time, and dummy variables for day of the week.5 For the two Economy 7 classes there's an extra refinement: the GADs are split into switched load and base load, using sample customers' information about their electric heating and the times their consumption is recorded against the low register.5 That separation matters, because switched heating load responds to the switching regime rather than to weather in the same way. When real behaviour shifts sharply — as it did during the Covid-19 lockdowns — the regression picks it up only once the sample data flows through, which is a useful illustration of the lag inherent in a modelled shape.42
The Profile Administrator produces regression coefficients. The SVAA then takes each day's out-turn temperature and sunset data. The temperature is supplied daily by the Met Office, one figure per GSP Group, from weather stations approved by the Supplier Volume AllocationSupplier Volume Allocation: the settlement arrangements for meters settled by profile rather than mandated half-hourly. Group. From these, the SVAA computes Daily Profile Coefficients and Period Profile Class Coefficients for every Settlement Period.1536
Suppliers receive these as the D0018The standard data report that lists, for each half hour, which meter register was recording. daily and D0028 standing Profile data reports whenever the Daily Profile Production Run happens; regression coefficients arrive with MDDMarket Domain Data: the central reference dataset Elexon publishes, holding the codes and tables everyone settles against..15
While the sample ran, profiling deliverables were refreshed twice a year, each built from the previous three years of sample data.35 Before anything could be used in settlement, the analysis and validation findings went to the Supplier Volume Allocation Group (SVGA governance group that reviews and approves the profiling data used in settlement each year.), which decided whether to approve the new set for the following BSCBalancing and Settlement Code: the industry rulebook that governs electricity settlement, administered by Elexon. Year. Approved coefficients then sit in MDD.15
Why two identical households in different parts of Great Britain pay different amounts — and how a supplier (and the price cap) builds a unit rate and standing charge from the ground up.
A retail price is a stack of costs plus a margin. Some components are essentially national; others vary by region — which is exactly why the regime tracks GSP GroupsGrid Supply Point Group: one of 14 regional areas. Profiles, losses and reconciliation are handled per region.. The big regional driver is the cost of the local distribution network: sparsely populated areas cost more per customer to serve.45 Profiling matters here too — a peaky profile costs more to buy at wholesale than a flat one, because when you consume changes what the energy costs.
| Component | Roughly… | Regional? |
|---|---|---|
| Wholesale energy | Buying the kWh, shaped to the customer's profile, plus the Capacity MarketA scheme that pays providers to be available when the system is under stress, funded by suppliers. | National (shape-sensitive) |
| Network — DUoSDistribution Use of System charges: what suppliers pay the local distribution network operator to carry electricity over its lower-voltage network. | Distribution Use of System, set per DNODistribution Network Operator: the company that owns and runs the local electricity network in a region. region | Strongly regional |
| Network — TNUoSTransmission Network Use of System charges: the cost of the high-voltage transmission network. Charges to suppliers vary by region. & BSUoSBalancing Services Use of System charges: recover the system operator's cost of balancing the system in real time, at a single national rate. | Transmission and balancing services | TNUoS varies by region; BSUoS is national |
| Policy & social | RORenewables Obligation: requires suppliers to source a share of their electricity from renewable generation, funded through bills., FiTFeed-in Tariffs: payments to small-scale generators such as rooftop solar, under a scheme closed to new applicants in 2019 and funded through suppliers., CfDContracts for Difference: the government's main support scheme for new low-carbon generation, funded by a levy on suppliers., WHDWarm Home Discount: an annual bill rebate for eligible low-income households, funded through all customers' bills., and others | Mostly national (AAHEDCAssistance for Areas with High Electricity Distribution Costs: a charge on suppliers across Great Britain that lowers distribution costs for customers in the North of Scotland. supports the North of Scotland) |
| Losses | The extra energy bought to cover network losses | Regional |
| Operating cost + margin | Serving the customer, plus EBITEarnings Before Interest and Tax: the profit margin the price cap allows a supplier. and a risk allowance | National |
What a typical home pays for electricity only at the cap in a year, and where that money goes. Figures are for Direct Debit on a single-rate meter using 2,500 kWh a year, in an average region of Great Britain. There is no VAT on electricity this quarter.46
The breakdown excludes payment method levelisation, an Ofgem adjustment that evens out certain cost differences between the ways customers pay, so it totals £854.72. The published average unit rateThe price per kWh of energy used. and standing charge include it, and at 2,500 kWh a year give about £858.4546 Ofgem’s adjustment allowance is zero this quarter. Percentages are shares of £854.72.
Ofgem's default tariff cap isn't one national number — there are separate caps in each of the 14 supply regions, reflecting those regional network costs.47 The headline figure you see in the news is a GB average for a typical direct-debit household; underneath it sit 14 regional sets of unit rates and standing charges, reviewed every three months.45
From 1 October 2026 the cap is £1,723 a year for a typical household using both electricity and gas and paying by Direct Debit. That is up 4% (about £60) on the £1,663 that applied from July to September, driven mainly by higher wholesale gas prices.4849 For electricity alone, a typical Direct Debit home on a single-rate meter pays about £858 a year at the average rates, and Figure 8 shows where that money goes.45
The £1,723 cap already includes a temporary cut in VAT on domestic electricity, from 5% to 0% between 1 October 2026 and 31 March 2027; Ofgem says the cap would otherwise have been about £45 higher. VAT on gas stays at 5%. Because of the VAT change, electricity prices from October cannot be compared directly with earlier quarters.4549
Across the 14 regions, Merseyside & North Wales is the most expensive for electricity, with both the highest unit rate (27.86p per kWh) and the highest standing charge (67.66p a day). Which region is cheapest depends on what you compare: the East Midlands has the lowest unit rate (25.36p) and London the lowest standing charge (42.92p). Rates also differ by payment method and meter type.4550
On 1 July 2026 Ofgem updated the TDCVTypical Domestic Consumption Values: Ofgem's assumed annual use for a typical home, used to quote the price cap., the benchmark volumes it uses to turn unit rates into a headline annual bill. Typical electricity use fell from 2,700 to 2,500 kWh (−7%) and gas from 11,500 to 9,500 kWh (−17%), reflecting genuinely falling household consumption.51 The same unit rates therefore produce a different annual figure depending on which benchmark is used. The July to September cap, for example, was £1,663 on the new benchmark and £1,862 on the old one; the £1,862 figure is the like-for-like comparison with April’s £1,641. Nothing about the pence per kWh differs between the two, and headline figures from July onwards use the new benchmark.51
There's a second-order effect worth noting, because it cuts against the intuition that a lower benchmark simply means a lower quoted bill. Some fixed costs — a share of network charges and supplier operating costs — are recovered through the unit rate. Spreading those over less assumed consumption means the unit rate has to rise to recover the same money: Ofgem lifted the electricity unit rate by 0.8% and gas by 1.3% alongside the TDCV change.5152
The breakdown comes from Ofgem’s default tariff cap level model for 1 October to 31 December 2026: single-rate electricity, paid by Direct Debit (which Ofgem calls “other payment method”), at typical consumption, as the average across GB regions.46 Ofgem’s cost lines are grouped into the categories Ofgem uses in its own published breakdown. Wholesale combines the direct cost of the electricity with the Capacity Market. Operating costs and industry charges combine core operating costs, industry charges and the smart metering net cost change, which is slightly negative this quarter.
The model’s figures come before payment method levelisation, which is why they total £854.72 rather than the roughly £858 implied by the published average rates. Each region has its own cap, and rates for prepayment, standard credit and Economy 7A two-rate tariff with a cheaper seven-hour overnight register. meters differ. Every figure changes each quarter.
The optional deep end: the shared rulebook that keeps everyone's codes consistent, the cast of agents who move the data, and the timetable over which settlement is run and re-run until it's final.
Market Domain Data (MDDMarket Domain Data: the central reference dataset Elexon publishes, holding the codes and tables everyone settles against.) is the central reference dataset ElexonThe organisation that administers the Balancing and Settlement Code and runs central settlement. distributes so that every supplier and agent uses the same definitions. It holds the valid Profile ClassesOne of eight standard customer types (for example, a domestic single-rate home) used to shape estimated demand., SSCsStandard Settlement Configuration: a code saying how many registers a meter has and which time windows group them., TPRsTime Pattern Regime: the switching pattern that says which half hours a particular meter register records in. and their valid combinations, Meter Timeswitch Codes, Line Loss FactorThe factor that scales metered use up to cover energy lost in the distribution network. Classes, GSP GroupsGrid Supply Point Group: one of 14 regional areas. Profiles, losses and reconciliation are handled per region., market participant IDs, and the AFYCAverage Fraction of Yearly Consumption: the share of a year's use that a profile puts on each register. and profile data used in settlement.23 Without a single source of truth here, two parties could process the same supply differently and settlement wouldn't reconcile.
MDD is exactly what MHHSMarket-wide Half-Hourly Settlement: the reform settling every meter half-hourly, using actual half-hourly data wherever a meter provides it. replaces with Industry Standing Data (ISDIndustry Standing Data: the MHHS replacement for Market Domain Data, the shared reference data.) — an enhanced, more automated reference service.53 The two co-exist through the transition; some MDD tables (those only needed for NHHNon-Half-Hourly: a meter or supply settled on estimates and a profile rather than on actual half-hourly readings. profiling) are retired at the end of it. That is the MHHS transition, covered in Parts 06–09.
Under the BSCBalancing and Settlement Code: the industry rulebook that governs electricity settlement, administered by Elexon.'s Supplier Volume AllocationSupplier Volume Allocation: the settlement arrangements for meters settled by profile rather than mandated half-hourly. arrangements, several roles handle a supply point's data on the supplier's behalf:5
Under MHHS several of these are renamed and re-cut — Meter Operator → Metering Service, Data Collector → Data Service, aggregation → the Market-wide Data Service — but that's the new regime.
Because real readings arrive over months, a Settlement Day isn't settled once — it's run repeatedly, each run swapping more estimates for actual data. There are six runs for each Settlement Day: IIInterim Information: an early, non-binding settlement run made before any money moves., SFInitial Settlement: the first binding settlement run for a day, about three weeks (15 working days) later, where money first changes hands., R1A reconciliation run: a re-run of a day's settlement as more actual meter readings arrive., R2A reconciliation run: a later re-run of a day's settlement as more readings arrive., R3A reconciliation run: a still-later re-run of a day's settlement as more readings arrive. and RFFinal Reconciliation: the last scheduled settlement run for a day, after which its figures are treated as final., with a DFDispute Final: an extra settlement run used only if a settlement dispute is raised. (Dispute Final) run if volumes are still disputed.5455
Suppliers must hit rising NHH performance levels — 30%, 60%, 80%, then 97% of energy on actual (Annualised Advance) data by RF.57 Elexon has compressed this timetable over the years, and MHHS overhauls it again, moving toward much faster settlement once migration completes.
What Market-wide Half-Hourly Settlement replaces and what it keeps: the new central services and market segments, how a half-hourly volume is produced with and without actual data, the compressed settlement timetable, and the commercial consequences for suppliers and customers.
Market-wide Half-Hourly Settlement is one of the biggest changes to GB electricity settlement since retail competition began in the late 1990s.6 It settles every supply point half-hourly, using the readings a meter actually records wherever they exist, instead of estimating them.
Everything in Parts 00–05 still applies today to every supply point that has not yet moved across: around 40% of them in late August 2026.62 The underlying objective remains the same: to produce a half-hourly volume for each supplier so that the market can be settled and imbalance charges calculated. What changes is how that volume is produced, in five ways, which this Part takes in turn:
Formally, MHHS is delivered through the BSCBalancing and Settlement Code: the industry rulebook that governs electricity settlement, administered by Elexon. by Modification P478The Balancing and Settlement Code change that delivers Market-wide Half-Hourly Settlement., with ElexonThe organisation that administers the Balancing and Settlement Code and runs central settlement. leading the programme as Senior Responsible Owner. The Data Communications Company adds new smart-data services, and the Retail Energy Code adds a new registration service.6
Under the current regime, an NHHNon-Half-Hourly: a meter or supply settled on estimates and a profile rather than on actual half-hourly readings. customer’s half-hourly use is estimated: their annual figure is spread across the half hours using the profile for their Profile Class (Part 03). Under MHHSMarket-wide Half-Hourly Settlement: the reform settling every meter half-hourly, using actual half-hourly data wherever a meter provides it., if a smart meter records actual half-hourly readings, the customer is settled on those readings. That is measurement, not estimation.
Sometimes half-hourly readings aren’t available: the meter is a traditional, non-smart one, or a smart meter’s data has a gap. For those cases, a new Load Shaping ServiceThe MHHS service that produces Load Shapes from the real half-hourly data of similar customers. (LSSLoad Shaping Service: the new MHHS service that produces Load Shapes from real half-hourly data.) works out typical half-hourly patterns, called Load ShapesUnder MHHS, the average of the actual half-hourly consumption of a group of similar customers on a given day., from the actual readings of similar customers. It then uses them to spread a meter reading or a daily total across the half hours. The LSS is the direct successor to profiling.59
The central calculations move to a new set of Elexon services, replacing the old Supplier Volume Allocation (SVASupplier Volume Allocation: the settlement arrangements for meters settled by profile rather than mandated half-hourly.) systems described in Part 05:
Elexon runs these systems, with the DCCData Communications Company: the body that runs the national smart-metering communications network. providing smart meter data and the Retail Energy Code Company running registration.663
The companies that look after meters and their data, the agents from Part 05, get new names and new boundaries. Their jobs are now split by type of meter, into three market segments: smart (which also covers traditional meters), advanced and unmetered.
The reference data moves too. The SSCStandard Settlement Configuration: a code saying how many registers a meter has and which time windows group them. and TPRTime Pattern Regime: the switching pattern that says which half hours a particular meter register records in. tables from Part 02 move from MDDMarket Domain Data: the central reference dataset Elexon publishes, holding the codes and tables everyone settles against. to the Retail Energy Code (RECRetail Energy Code: the code that, under MHHS, takes over some reference data such as SSCs and TPRs.),24 and ISDIndustry Standing Data: the MHHS replacement for Market Domain Data, the shared reference data. becomes the main reference dataset for settlement.65
MHHS runs to a plan of numbered milestones. Ofgem reset that plan in late 2024 through Change Request CR055A formal change that re-planned and extended the MHHS delivery timetable., moving the key dates back by roughly seven months.66 As of autumn 2026, well over half of all supply points have moved across to MHHS.
Around 33 million MPANs have to move across within an 18-month window.67 Migration began on 22 October 2025, with suppliers moving their customers in planned batches. In July 2026 the MHHS Programme announced that half of all MPANs had migrated, and by 28 August 2026 it reported 20.2 million, about 60% of those in scope.62 Elexon plans for about 80% by October 2026. That is a target, not yet a result, and much of the remaining volume is scheduled late in the plan.68 Elexon also publishes a dashboard ranking suppliers by how much of their customer base has already moved across.69
The other headline change is speed. Under the current regime, a day isn’t finally settled until the final reconciliation run, 14 months later (Part 05). MHHS cuts that to four months, and brings the first financial settlement run (SFInitial Settlement: the first binding settlement run for a day, about three weeks (15 working days) later, where money first changes hands.) forward from 15 working days to seven.61
This happens in steps rather than all at once, and each step applies to settlement days from a given date:
Because the steps are tied to settlement days, a day in October 2026 reaches its seven-month final run in spring 2027. That is why the programme describes the seven-month timetable as starting in April 2027.71 As the final run moves earlier, two reconciliation runs disappear: the final run (RFFinal Reconciliation: the last scheduled settlement run for a day, after which its figures are treated as final.) takes the place of R3A reconciliation run: a still-later re-run of a day's settlement as more readings arrive. and then of R2A reconciliation run: a later re-run of a day's settlement as more readings arrive..6171 The R1A reconciliation run: a re-run of a day's settlement as more actual meter readings arrive. run also moves from 38 to 29 working days, and the Dispute FinalDispute Final: an extra settlement run used only if a settlement dispute is raised. run from 28 months to 20.71
Because most consumption is now measured rather than estimated, there is far less to correct later. Under the old regime, large adjustments came as estimated annual figures (EACsEstimated Annual Consumption: an estimate of a customer's yearly use, used before a fresh meter reading.) were replaced, over many months, by figures based on actual meter readings (AAsAnnualised Advance: a customer's yearly use recalculated from an actual meter reading.). Under MHHS those swings largely disappear.
MHHS also changes how settlement data moves between the parties, from point-to-point flows to a single hub, the Data Integration Platform. Part 07 explains how that works.6
Part 06 set out what changes. This Part follows a meter through MHHS step by step, so you can compare it with the profiling engine in Part 03 and see exactly where the estimation goes.
Under the current regime, the first question about a supply point is its Measurement ClassWhether a meter is settled on actual half-hourly readings, or on estimates and a profile.: is it settled half-hourly or not? Under MHHS that question disappears, because everything is settled half-hourly. Instead, MHHSMarket-wide Half-Hourly Settlement: the reform settling every meter half-hourly, using actual half-hourly data wherever a meter provides it. places each supply point in one of three market segments, based on its type of meter. The segment decides which services handle it:72
One point that surprises people: a traditional meter with no communications at all sits in the Smart segment. The segment names the set of services that handle a meter, not the technology inside it.
The central work is carried out by ElexonThe organisation that administers the Balancing and Settlement Code and runs central settlement. through four services. Formally, these are the four parts of a single role called Central Settlement.72 BSCP703The BSC procedure for Elexon's central MHHS services: the Load Shaping Service, Market-wide Data Service, Volume Allocation Service and Industry Standing Data. sets out what each does:63
This is the single biggest new idea in MHHS, so it is worth being precise. BSCP703 defines it like this:63
In plain terms, a Load Shape is the average half-hourly pattern that a group of similar customers actually followed on a given day, worked out from their real meter readings. Compare that with the profiles in Part 03, which come from a statistical model built on a small research sample of customers and adjusted for each day’s temperature and sunset. A Load Shape is a measurement rather than a model, and its “sample” is the whole market rather than a research panel.
That needs enough data. A Load Shape for a category is only built from that category's own meters once at least 50 of them have actual data. Below that, the LSS averages the category across all GSP Groups; failing that, it reuses the most recent shape for the same type of day; and as a last resort it applies a flat shape. Early in migration some categories had not yet reached the threshold, so their shapes leaned on these fallbacks.7475
Each day’s Load Shapes are produced four calendar days later, in the Load Shaping Run at Calendar Day + 4. The LSS then publishes them to the MDSMarket-wide Data Service: the MHHS central service that aggregates half-hourly volumes., to suppliers and to each of the Data Services.63 The detailed calculations are set out in BSCBalancing and Settlement Code: the industry rulebook that governs electricity settlement, administered by Elexon. Section S, Annex S-3.63
Not every supply point will provide 48 good readings a day. MHHS deals with that through a clear order of preference: actual data wherever it exists, and Load Shapes only to fill the gaps:59
Where a smart or advanced meter provides a reading for each half hour, those readings are checked and used directly. Nothing is shaped or estimated. This is the case MHHS is built for, and once migration is complete it should cover the great majority of consumption.
A traditional meter still only gives a total: a register reading, or a figure for a whole day. The processing part of the Smart Data Service spreads that total across the half hours using the right Load Shape.59 This works just like profiling, a total spread over a shape, except that the shape now comes from the real half-hourly readings of similar customers instead of from a statistical model.
Where a smart meter’s half-hourly readings are faulty or simply missing, Load Shapes are used to estimate the missing values, and to fill in a default value where there is no data at all.59 This is the safety net. It is also why data quality becomes a commercial issue: the more data a supplier fails to collect, the more of its customers are settled on an average rather than on what they actually did. In spring 2026 Elexon reported that a significant proportion of migrated MPANs were having their consumption defaulted at the first settlement run because data services had not submitted their data in time.76
The other structural change is how data moves between the companies involved. Today it mostly travels point to point: each agent sends each data file to every party that needs it. Under MHHS, each party publishes its data once to the Data Integration PlatformThe central hub under MHHS where each piece of data is published once and shared with everyone who needs it., and every party that needs it picks it up from there.72 That is what makes it practical to settle tens of millions of meters half hour by half hour: from May 2027 Elexon expects to process up to 500 billion half-hourly meter readings a year.6
The SSC and TPR codes from Part 02 don’t disappear, but their role changes. The detail matters most to anyone who runs supplier systems:24
| Item | Where it lands |
|---|---|
| SSCStandard Settlement Configuration: a code saying how many registers a meter has and which time windows group them./TPRTime Pattern Regime: the switching pattern that says which half hours a particular meter register records in. in settlement | Not used. The MHHS arrangements do not use SSC and TPR data to settle. ISD does not include them. |
| SSC on the supply point | Still mandatory for Traditional metering and populated in the registration service; optional for Smart and Advanced. It's carried in the MHHS interfaces and market messages, and since September 2025 the SSC Id has replaced the MTCMeter Timeswitch Code: a code describing a meter's switching arrangement and payment type. on the top line of the Supply Number, for all MPANsMeter Point Administration Number: the number that identifies an electricity supply point, printed on bills as a 13-digit core plus a top line of supply details..2477 |
| Ongoing maintenance | Moves to the Retail Energy Code. The RECRetail Energy Code: the code that, under MHHS, takes over some reference data such as SSCs and TPRs. Code Manager maintains a Meter Configuration Table under Schedule 14 (Metering Operations), as a single nationwide valid set that no longer varies by distributor. |
| TPR data sharing | Carried on the REC Data Transfer Network via the Notification of Old Supplier Information flow, and with Meter Technical Details for traditional meters. |
| Historic MDDMarket Domain Data: the central reference dataset Elexon publishes, holding the codes and tables everyone settles against. | A static version planned to be retained for five years, visible but not actively managed: no new valid combinations can be added under the BSC. Elexon is consulting on how MDD is frozen and retired, until 26 October 2026.78 |
| Teleswitch tables | Left in the frozen MDD and not maintained by the REC. Only timeswitch TPRs get future changes, consistent with RTSRadio Teleswitch Service: an older system that switched meters between rates using a radio signal. having ended in June 2026. |
So the codes survive as a way of describing how a meter is set up, but no longer decide which half hours energy is allocated to. The time pattern stops being part of settlement and becomes simply a description of the tariff.
Settlement still does the same job under MHHS, but almost every part of the machinery changes. This table puts each part of the current regime, from Parts 01–05, next to what replaces it under MHHSMarket-wide Half-Hourly Settlement: the reform settling every meter half-hourly, using actual half-hourly data wherever a meter provides it..
| What | Current regime (pre-MHHS) | MHHS |
|---|---|---|
| Settlement basis | Estimated half-hourly volume for NHHNon-Half-Hourly: a meter or supply settled on estimates and a profile rather than on actual half-hourly readings. supplies | Measured half-hourly volume; estimation only where data is missing |
| Shape engine | A statistical model built from a research sample of customers, turned into daily values by the SVAASupplier Volume Allocation Agent: the central agent that turns profiles into each supplier's half-hourly volumes. using each day’s temperature and sunset | Load ShapesUnder MHHS, the average of the actual half-hourly consumption of a group of similar customers on a given day.: the average half-hourly pattern that similar customers actually followed each day, for each Load Shape CategoryThe grouping, defined in Industry Standing Data, for which a single Load Shape is calculated under MHHS. and each GSP GroupGrid Supply Point Group: one of 14 regional areas. Profiles, losses and reconciliation are handled per region., worked out from real meter readings59 |
| Profile ClassesOne of eight standard customer types (for example, a domestic single-rate home) used to shape estimated demand. | PC1–4 profiled; PC5–8 already mandatorily half-hourly since P272The 2017 change that moved larger meters (Profile Classes 5 to 8) onto half-hourly settlement. in April 201716 | Still given to traditional meters, but no longer used to set the half-hourly shape |
| Market split | Measurement ClassWhether a meter is settled on actual half-hourly readings, or on estimates and a profile.: half-hourly vs non-half-hourly | Market segment, based on the type of meter: Smart, Advanced or Unmetered72 |
| Time-of-use | SSCStandard Settlement Configuration: a code saying how many registers a meter has and which time windows group them. + TPRTime Pattern Regime: the switching pattern that says which half hours a particular meter register records in.: a fixed timetable held in central reference data, which cannot represent a tariff that changes from day to day24 | Actual half-hourly volumes; the tariff no longer has to be registered as a timetable |
| Reference data | Market Domain Data (MDDMarket Domain Data: the central reference dataset Elexon publishes, holding the codes and tables everyone settles against.); SSC/TPR held in MDD | Industry Standing Data (ISDIndustry Standing Data: the MHHS replacement for Market Domain Data, the shared reference data.); SSC/TPR maintenance moves to the RECRetail Energy Code: the code that, under MHHS, takes over some reference data such as SSCs and TPRs., historic MDD to be frozen (its retirement is under consultation)5378 |
| Metering | Meter OperatorThe party responsible for installing and maintaining the physical meter. (MOP) | Metering Services: smart and traditional meters (MSS), and advanced meters (MSA) |
| Data collection | Data CollectorThe agent that retrieves meter readings and, for non-half-hourly meters, works out the EAC and AA. (NHHDC / HHDC) | A Data Service for each segment; the Meter Data Retriever (MDRMeter Data Retriever: a DCC user role, used as part of the Smart Data Service, that retrieves smart meter data for settlement.) pulls smart data via the DCCData Communications Company: the body that runs the national smart-metering communications network. |
| Aggregation | Data AggregatorThe agent that adds up settled volumes across all of a supplier's meters. (NHHDA / HHDA) | Market-wide Data Service (MDSMarket-wide Data Service: the MHHS central service that aggregates half-hourly volumes.) |
| Volume allocation | Supplier Volume Allocation Agent (SVAA) | Volume Allocation Service (VASVolume Allocation Service: the MHHS central service that allocates volumes to suppliers.) |
| Data sharing | Data sent point to point between the parties | Publish once to the Data Integration PlatformThe central hub under MHHS where each piece of data is published once and shared with everyone who needs it. (DIPData Integration Platform: the central hub under MHHS where data is published once and shared with all who need it.) |
| First settlement (SFInitial Settlement: the first binding settlement run for a day, about three weeks (15 working days) later, where money first changes hands.) | 15 working days after the Settlement Day | 7 working days (R1A reconciliation run: a re-run of a day's settlement as more actual meter readings arrive. also moves from 38 to 29 working days)6171 |
| Final reconciliation (RFFinal Reconciliation: the last scheduled settlement run for a day, after which its figures are treated as final.) | 14 months; runs IIInterim Information: an early, non-binding settlement run made before any money moves. / SF / R1 / R2A reconciliation run: a later re-run of a day's settlement as more readings arrive. / R3A reconciliation run: a still-later re-run of a day's settlement as more readings arrive. / RF, with DFDispute Final: an extra settlement run used only if a settlement dispute is raised. at 28 months if disputed56 | 4 months, staged via an interim 7-month step (planned for settlement days from 1 October 2026, then 4 months from 1 April 2027); fewer reconciliation runs, DF reduced to 20 months6171 |
| Reconciliation size | Large GSP Group CorrectionA factor, set for every half hour, that scales suppliers' allocated volumes (mainly the estimated ones) so a region's total matches the energy measured entering it., and big adjustments as estimated annual figures (EACsEstimated Annual Consumption: an estimate of a customer's yearly use, used before a fresh meter reading.) are replaced by figures from actual readings (AAsAnnualised Advance: a customer's yearly use recalculated from an actual meter reading.) over many months | Much smaller once migration is complete and data flows reliably, because most volume is then measured by the first settlement run. During migration, missing data submissions still caused defaults.76 |
| Customer granularity | One annual figure, shaped to an average pattern | Actual half-hourly use, enabling time-of-useA tariff whose price varies by time of day. tariffs and flexibility |
The mechanics matter because of what they change in practice, and the same reform looks different from a supplier’s point of view than from a customer’s.
This section is analytical. The factual premises it rests on (the timetable change, the move to measured data, the programme obligations, the data-access rules) are footnoted to their sources. The conclusions drawn from them, about supplier risk, working capital, operational load and competitive positioning, are reasoned inferences rather than claims traceable to a single source.
Forecasting and imbalance. Settling on actual half-hourly data removes most of the profiling error baked into today's NHHNon-Half-Hourly: a meter or supply settled on estimates and a profile rather than on actual half-hourly readings. settlement.59 The demand a supplier is settled on stops being an average shape and becomes its customers’ real pattern of use. That makes demand easier to forecast, and cuts the imbalance costs that arose purely from estimation errors. The flip side is that a supplier is now exposed to the quality of its own data, rather than sheltered by a shared profile.
Cash and reconciliation. Cutting final reconciliation from fourteen months to four means suppliers know their final settlement costs much sooner.61 Less money is tied up waiting for settlement to be finalised, which reduces the working capital suppliers need and makes their margins more predictable.
Data quality and automation. The flip side of a four-month window with a seven-working-day first settlement is that there is far less time to find and fix bad data before settlement closes. Fixing problems by hand doesn’t work with half-hourly data for every customer, so checking data, handling exceptions and monitoring data quality all have to be automated. For most supplier settlement teams this is the single biggest operational change.
Cost of change, and cost recovery. Suppliers must qualify, migrate every MPANMeter Point Administration Number: the number that identifies an electricity supply point, printed on bills as a 13-digit core plus a top line of supply details., re-engineer billing, forecasting and settlement systems, contract the new agent roles and integrate with the DIPData Integration Platform: the central hub under MHHS where data is published once and shared with all who need it.. That is a substantial programme, and CR055A formal change that re-planned and extended the MHHS delivery timetable. made it longer.6066 Against that, settlement that better reflects real costs helps suppliers recover their costs accurately, and reduces the cross-subsidies and estimation risk in the current model. Costs other than the energy itself, such as network and policy costs, are also allocated more accurately when they are applied to real half-hourly volumes.
New propositions. Half-hourly data is also an opportunity: genuine time-of-useA tariff whose price varies by time of day. tariffs, EVElectric vehicle. and heat-pump products, and flexibility or demand-response offerings become possible to design and settle.59 That makes MHHS a competitive opportunity, not just a compliance cost.
More accurate bills. Once their supply has migrated to MHHS and its data is flowing, customers with smart meters are settled on what they actually used, and when, rather than on an estimated average shape for their class.59 Settlement, and increasingly billing, reflects reality more closely.
Reward for flexibility. Because usage is now valued by time, suppliers can pass through cheaper off-peak periods and pay for load-shifting. Customers who can move their consumption, for example by charging an EV overnight or running a heat pump smartly, stand to lower their bills, and the system as a whole gets the flexibility it needs for Net Zero.79
A smart or advanced meter is needed to benefit fully. Customers still on traditional meters are settled using Load ShapesUnder MHHS, the average of the actual half-hourly consumption of a group of similar customers on a given day., the new equivalent of profiling, so the biggest benefits flow to those with smart metering and a time-varying tariff.
A data consideration. Market-wide half-hourly settlement means half-hourly consumption data is used for settlement across the board. The rules on using that data had to change to allow it. Ofgem’s 2019 decision made half-hourly data the default for settlement. Domestic customers can opt out and be settled on daily data instead; microbusinesses cannot opt out.80 Some customers will care about this.