The short version
The Q4 October 2026 price cap forecast moved again on 28 July, when E.ON Next published an updated estimate of £1,729. Next to Cornwall Insight's £1,849 and EDF Energy's £1,804, the three numbers for the October 2026 energy price cap sit close to £120 apart, a gap from modelling choices, not wholesale prices.
Ofgem confirms the actual Q4 cap at the 26 August price cap announcement, with new rates from 1 October. Households weighing whether to fix face an Ofgem October 2026 price cap forecast built differently across sources.
Three forecasts, three different starting points
Every price cap forecast answers the same question: what will a typical household's annual unit rates and standing charges add up to between 1 October and 31 December, with the disagreement sitting in the assumptions layered on top.
The Cornwall Insight Q4 2026 forecast of £1,849 uses the older Ofgem benchmark (2,700 kWh electricity, 11,500 kWh gas). The E.ON Next price cap forecast of £1,729, covered in SwitchInsights' TDCV review, uses the newer, lower benchmark (2,500 kWh, 9,500 kWh) Ofgem adopted from 1 July. The EDF Energy price cap forecast of £1,804 shares Cornwall Insight's older benchmark but nets off the 21 July VAT cut on domestic electricity, so the VAT cut energy price cap October 2026 interaction is usually quoted separately.
| Forecaster | Q4 2026 forecast | Consumption basis | VAT cut netted off |
|---|---|---|---|
| Cornwall Insight | £1,849 | Older benchmark | No |
| EDF Energy | £1,804 | Older benchmark | Yes |
| E.ON Next | £1,729 | Newer benchmark | No |
E.ON Next's number looks cheapest, but it is measured against lower assumed usage. Ofgem's Q3 figures showed a £199 gap between the benchmarks, and applying that gap to £1,729 puts its older-benchmark equivalent at roughly £1,928, the highest of the three.
What each scenario means for a typical dual fuel household bill October 2026
On the same older-benchmark basis, the three forecasts sit either side of the confirmed Q3 2026 cap of £1,862, with EDF Energy's VAT-adjusted model the only one meaningfully below it.
| Scenario | Annual (older benchmark) | Monthly | vs Q3 2026 (£1,862) |
|---|---|---|---|
| Current Q3 2026 cap (confirmed) | £1,862 | £155 | - |
| EDF Energy (VAT-adjusted) | £1,804 | £150 | -£58 (-3.1%) |
| Cornwall Insight | £1,849 | £154 | -£13 (-0.7%) |
| E.ON Next (adjusted to older benchmark) | £1,928 | £161 | +£66 (+3.5%) |
On its own newer-benchmark basis, E.ON Next's £1,729 is a 4% rise on Ofgem's confirmed Q3 newer-benchmark cap of £1,663.
The best fixed energy deals August 2026 already undercutting every scenario
Several of the cheapest fixed energy tariffs July 2026 on the market already beat all three forecasts, per tariff-tracker rates checked late June 2026.
| Supplier | Fixed tariff | Annual cost | Saving vs Q4 range |
|---|---|---|---|
| Fuse Energy | Fixed, 15 months | £1,567 | £237-£361 |
| E.ON Next | Next Fixed, 24 months | £1,706 | £98-£222 |
| Octopus Energy | 12-Month Fixed | £1,732 | £72-£196 |
| EDF Energy | Simply Fixed, to July 2027 | £1,733 | £71-£195 |
| ScottishPower | Fixed, to July 2027 | £1,777 | £27-£151 |
Even against EDF Energy's own VAT-adjusted forecast, every deal above comes out cheaper. Check current figures on the SwitchPilot tariff tracker, as rates move regularly.
Fix energy tariff before October 2026 cap: a checklist for 26 August
Weigh the fixed-tariff saving, the exit-fee risk and the 26 August deadline together, instead of ranking forecasters on which number looks cheapest.
- Compare the cheapest fix against the widest forecast range, not the middle one. Fixing then does not depend on which forecaster turns out right.
- Check your exit fee against your confidence in the forecast. A modest fee costs little to leave if the cap undercuts every forecast.
- If you are already on a fix that runs through winter, no action is needed.
- Watch the calendar, not just the price, since suppliers typically reprice fixed deals within days of the 26 August confirmation.
Every current fixed deal already undercuts the lowest Q4 forecast here, and choice narrows once the confirmed cap sets a new floor for supplier pricing.
Frequently asked questions
What is the Q4 October 2026 price cap forecast?
Forecasts for a typical dual-fuel household range from about £1,804 to £1,929 on the older consumption benchmark. Ofgem confirms the actual figure on 26 August.
When will Ofgem announce the October 2026 cap?
Ofgem confirms the Q4 2026 price cap on 26 August 2026. New rates take effect from 1 October and run until the end of December.
Should I fix my energy tariff now or wait until 26 August?
The cheapest fixed deals already undercut every forecast, so households able to commit to a 12 to 24-month contract without a heavy exit fee are generally better off fixing now.
Does the 21 July VAT cut affect the Q4 price cap forecast?
Only in models that net it off. EDF Energy's £1,804 forecast includes the roughly £45 VAT-cut saving; Cornwall Insight's £1,849 and E.ON Next's £1,729 do not.
Why does E.ON Next's forecast look lower than Cornwall Insight's?
It uses the newer, lower Ofgem consumption benchmark. Adjusted to Cornwall Insight's older basis, E.ON Next's read is the highest of the three, at close to £1,928.
Which fixed energy tariffs currently beat the Q4 forecast?
On late-June 2026 tariff-tracker data, Fuse Energy, E.ON Next, Octopus Energy, EDF Energy and ScottishPower all offer fixed deals below every Q4 forecast scenario, from £1,567 to £1,777 a year.