When a household or business pays an energy bill, only part of what they pay is the cost of the electricity or gas itself. The rest, often somewhere between a third and a half of a typical bill, pays for the networks that deliver the energy, the schemes that subsidise low-carbon generation, the programmes that support vulnerable customers, and the cost of keeping the system balanced second by second. Collectively the industry calls these non-energy costs.
Almost none of these charges are set continuously. They are fixed on published timetables, usually annually and sometimes quarterly, by a mix of network companies, the system operator, the regulator and government. Each one has a forecast stage, a draft stage and a final confirmed stage, and each of those stages lands on a particular month. This calendar maps that cycle so you can see, at a glance, which charges move when.
For anyone pricing a supply contract, forecasting a cost stack or explaining a bill increase, the publication date is often as important as the number itself. A supplier quoting a two-year fixed contract in November is pricing a period for which several major charges have only been forecast, not confirmed.
The industry works to a regulatory year running from 1 April to 31 March, so most annual charges take effect on 1 April and are confirmed in the preceding winter.
The calendar groups events into five colour-coded categories.
Each row in the calendar below marks the months in which that event occurs, with a coloured dot showing which category it belongs to. Clicking a row opens the detail panel, which explains what is published, why it matters, the timing rule that governs it, and a link to the authoritative source.
The intention is that this sits next to a cost model rather than replacing one. It answers the question "when does this number become real?", not "what is the number?". For the latter, follow the source links, which point at the network companies, the system operator and the regulator directly.