Ofgem’s price cap rewrite: what it means for your energy bill

The energy price cap is about to be recalculated, and for once the change is not about the headline number. Ofgem has announced it will revise the methodology that determines how the cap is set for millions of households on default tariffs. The cap itself will still rise or fall with wholesale costs, but the formula behind it, the bits that allocate network charges, policy costs, and supplier margins, is being rewritten.

As reported by MSN, the consultation documents show Ofgem wants to “better align” the cap with actual supplier costs. That sounds like technocratic housekeeping. For a household in a three-bed semi in Leeds paying by prepayment meter, it could mean a difference of roughly £25 a year, up or down depending on how the new formula weights standing charges versus unit rates.

Who qualifies, and who doesn’t

The price cap applies to roughly 28 million households on standard variable tariffs (SVTs) and default deals. If you are on a fixed tariff, the cap does not directly apply to you, but the market rates you are offered are influenced by it. The calculation change will affect: households paying by direct debit (about 70% of all customers), those using prepayment meters (around 4 million), and standard credit customers (paying on receipt of bill, often higher rates).

Ofgem’s proposed changes include updating the weighting of payment method costs. Currently, prepayment customers pay a higher standing charge because of higher operational costs. The new formula may narrow that gap, good news for the 4 million on prepayment, but it could mean a slight increase for direct debit households. The net effect is likely small: think £10–£30 per year, not hundreds.

What it costs a typical 3-bed semi

Take a typical semi-detached house using 12,000 kWh of gas and 2,900 kWh of electricity per year (Ofgem’s benchmark). Under the current cap (July–September 2025), the typical annual bill is around £1,568. The calculation change might shift that by plus or minus £20–£30, depending on region and payment method.

But the real risk is not the change itself, it is the uncertainty. The cap is supposed to protect households from excessive prices. If the formula becomes less transparent, or if it shifts costs from one group to another without clear justification, trust erodes. Ofgem says the revision will “improve accuracy”, but critics point out that the cap already lags wholesale prices by several months.

For homeowners considering eco-upgrades, the message is clear: the cap is a blunt instrument. A heat pump or solar panels cut your exposure to unit price changes entirely. The Energy Saving Trust estimates a typical heat pump installation can reduce heating bills by 20–40% compared to a gas boiler, depending on the property’s insulation. That is a far more reliable hedge than hoping the cap calculation works in your favour.

What this misses, and what you should do

But the Ofgem consultation does not address the structural problem: the UK’s energy system still relies heavily on gas-fired generation, which sets the wholesale price for electricity. Until that changes, the cap will remain a bungee cord tied to global gas markets. The proposed revision tweaks the rope, it does not cut it.

Households on SVTs should check if they can switch to a fixed tariff. MoneySavingExpert’s Energy Club and Ofgem’s own comparison tools can show current fixed deals. If you are in a region with higher standing charges (typically the North of Scotland or the South West), the cap revision may narrow that gap, but do not wait, fix for 12 months if you find a rate below the current cap.

For those serious about reducing bills long-term, the government’s Boiler Upgrade Scheme offers £7,500 towards a heat pump, and the Great British Insulation Scheme provides free or discounted loft and cavity wall insulation. These are not affected by the cap formula. They are the real escape route from price cap roulette.