Use annual kWh
Monthly Direct Debit can be too high, too low or seasonal. Annual usage is the clean comparison input.
Do this before you press switch
Check exit fees
Fixed tariffs may have exit fees if you leave early, but Citizens Advice says you can usually switch fee-free in the final 49 days.
Take a meter reading
Record readings on switch day and keep screenshots of quoted rates, dates and credits.
Sources and useful links
Worked examples — see the maths on real numbers
How energy switching savings actually work out in 2026, including the price cap dynamics.
Average UK home on default Ofgem cap
| Energy supplier | Default tariff (Ofgem cap) |
| Annual usage (Ofgem 2026 typical) | 2,500 kWh electricity + 9,500 kWh gas |
| Ofgem cap from 1 October 2026 | £1,723/year |
| Illustrative fixed deal, 8% below cap | £1,585/year |
The maths:
- Cap rate already includes regional standing charges
- Fixed deal saving: £1,723 − £1,585 = £138/year
- Fixed deal locks in price for 12 months — protection if cap rises
- Risk if cap falls: stuck paying higher fixed price for the remainder
- Switching fee: usually £0 for online switches
Result: A typical UK home saves roughly £138/year on a competitive fixed deal vs the default cap. Deals available at any moment move around, so put your own quote into the calculator rather than relying on this figure. Switching is worthwhile annually but the savings are now much smaller than the £300-£500 averages from before the 2022 energy crisis tightened the market.
High-usage household (heat pump or all-electric)
| Electricity usage | 7,500 kWh/year |
| Gas usage | 0 (all-electric) |
| Standard tariff cost | ~£2,200/year |
| EV/heat pump time-of-use tariff | ~£1,650/year (savings driven by night-rate usage) |
The maths:
- Time-of-use tariff: cheap night rate (~7p/kWh) for 6-8 hours, expensive peak rate (~38p/kWh) for 6 hours, standard rate other times
- Match usage to night rate: heat pump pre-charge water tank overnight, EV charge after midnight, dishwasher/laundry timer
- If 60% of usage shifts to night rate: £2,200 → £1,650 = £550/year saving
- Behavioural shift required — but technology (timers, smart plugs) can automate most of it
Result: For all-electric homes (heat pump, EV, induction cooking), time-of-use tariffs can save £400-£700/year — substantially more than traditional gas+electric switching. Octopus Agile takes this further with half-hourly variable pricing, sometimes including negative prices when wind generation is high.
Figures use 2026/27 UK tax-year rates and thresholds. Always verify against your specific payslip or tax statement before acting.
Editorial accountability
Open Trust Centre →
How UK Tax Drag holds itself to account
Every page is reviewed against the editorial standards, written from primary sources and sourced openly, with corrections listed in the changelog. No affiliate revenue. No sponsored content. No paid placements.
UK Tax Drag is an independent publication by Finsolve Consulting Limited, not affiliated with or endorsed by HMRC, GOV.UK or any government body.