Lock in a 12-month energy fix today — Cornwall Insight says the price cap jumps to £1,850 in July

Ofgem sets the price cap every three months. It is the maximum suppliers can charge customers on a standard variable tariff. People treat it like a guarantee. It is not. It is a delayed mirror of wholesale gas costs from a few months ago.

The April to June cap of £1,641 reflects wholesale prices from a calmer winter. The July to September cap reflects what happened after the Iran conflict began — and wholesale gas prices have been volatile since. Cornwall Insight's £1,850 forecast assumes prices stabilise. If they do not, the actual cap will be higher.

Fixed tariffs at or below the current cap exist today. They will be much harder to find on 28 May, when suppliers price their books against the new cap level. Whatever the announcement says on 27 May, the deals priced before that date were priced against £1,641 — not £1,850. That is the arbitrage you are walking past if you wait.

Look at the cost breakdown Ofgem publishes for the current cap. Wholesale costs fell £38 between January and April. Network costs rose £66. Government social and environmental schemes fell £130 — the single biggest mover, and the reason the cap dropped at all. Without that policy cost reduction, your bill would have gone up this April.

That policy reduction is a one-off. It will not repeat in July. So the July cap is essentially the April cap, plus whatever wholesale gas has done since the Iran conflict pushed energy markets into volatility. The Bank of England held its base rate at 3.75% on 30 April and explicitly warned it could raise rates if the war fuels inflation — which is a cleaner read of where the BoE expects energy costs to go than any consumer-facing forecast.

A fix at £1,650 a year today is not a great deal historically. It is a great deal compared to £1,850 starting in 90 days.

When Russian gas hit Britain in 2022, the government stepped in with the Energy Price Guarantee. Universal support. Every household got the same cap regardless of income.

The Chancellor has confirmed any Iran-war winter support will not work that way. It will be means-tested and targeted at the lowest-income households. If you have a salary, a mortgage, or moderate savings, you are not the target.

This matters because it removes the silent insurance that variable-tariff households relied on last time. In 2022, holding the variable rate looked clever because the government socialised the loss when prices spiked. In 2026, that backstop is gone for most households. You are now bearing the full cost of a winter spike yourself — unless you have already fixed.

The Resolution Foundation estimates the average working-age household will be £480 worse off this year because of higher energy prices. That is the cost of doing nothing.

The maths is unsexy but decisive. A typical household paying the current £1,641 cap who fixes today at £1,650 for 12 months is roughly flat versus the cap for the next two months — and likely £150 to £250 better off across the rest of the year if Cornwall Insight's £1,850 July forecast is anywhere close.

The blended cost row assumes two months at the £1,641 cap and ten months at £1,850 — roughly £1,798. That is £148 more than fixing. Across 800,000 households it is £118m. Across the 22m households on standard variable tariffs it is north of £3bn. None of that is in the official forecasts because the official forecasts are not allowed to assume behaviour change.

The arithmetic still works if Cornwall Insight's forecast is too high. If the July cap comes in at £1,750 instead, the fix still saves about £75. Below £1,700 and the fix breaks even. Below £1,650 and you lost — but every signal from the wholesale market and the BoE is pointing the other way.

Three checks before you sign a fixed tariff:

1. Exit fees. A 12-month fix with a £30 per fuel exit fee is fine. A 24-month fix with £125 per fuel is a trap if a ceasefire holds and wholesale prices fall hard. Fewer long-duration deals are available right now precisely because suppliers are protecting themselves against that scenario — read it as a signal, not a deal. The Citizens Advice supplier comparison guidance walks through the exit-fee structure on every major fixed product if you want to compare directly.

2. Standing charge versus unit rate. The current cap unit rates are 24.67p/kWh for electricity and 5.74p/kWh for gas, with daily standing charges of 57.21p (electricity) and 29.09p (gas). Fixed deals at parity or below on unit rate are the right ones. Fixed deals that cut the unit rate but bake in a higher standing charge punish low-usage households disproportionately — single-occupant flats especially. The MoneyHelper energy comparison guide has a worked breakdown for low-usage versus average-usage households.

3. Provider stability. The 2022 wave of supplier failures cost households real money even with the Supplier of Last Resort regime. Stick with the big six or established challengers (Octopus, OVO, EDF, British Gas) for a war-era fix. The credit risk discount on smaller suppliers is not worth the operational fragility right now.

For the broader cost-of-living context — including how energy prices interact with mortgages, savings rates, and your protected emergency fund — see our savings hub, the April cost-of-living analysis, and the comprehensive energy bills guide. If you are also weighing a mortgage decision in this same window, the mortgage fix-term debate covers the directly analogous trade-off.

The Resolution Foundation's £480 estimate is an average. The shape of the distribution matters. Lower-income households on means-tested benefits will see most of the energy hit absorbed by the new winter targeted-support scheme. Higher-income households with lower income-elasticity of demand (you are not going to stop heating the house in January because the bill went up) will eat the cost. The middle — roughly the £30,000 to £60,000 household income band — is the worst place to be. Too rich for support, not rich enough to absorb a £500 hit without rebalancing the budget.

A March 2026 BBC analysis of household types showed the typical mid-income family already running tight after April's energy bill drop was offset by water rate rises (+£30 average), council tax increases (capped at 4.99% in England), and BBC licence fee rises. A £200 quarterly energy bump in October will land on a budget that has no room for it. Fixing now spreads the cost predictably across 12 months at today's prices instead of stacking it onto one quarter at next quarter's prices.

The BoE's central scenario does have inflation falling back to 2% by 2027 — but its adverse scenario sees inflation peaking just above 6% before normalising. The variable cap is fully exposed to that adverse scenario. A 12-month fix is exposed only to the upside of the BoE's central case, not the downside of its adverse one. That asymmetry is what you are buying.

This article is for informational purposes only and does not constitute financial advice. You should seek independent financial advice before making any decisions about your energy supply, especially if you have specific accessibility needs (e.g. medical equipment that depends on continuous power) or are on a means-tested benefit that interacts with energy support payments. The case made here for fixing is one reading of the available data; the case for staying variable is genuine and is set out in our companion piece.