Fix for certainty
If the fixed quote is close to variable and your budget hates surprises, certainty has value even when the saving is small.
When a fix makes sense
Do not fix blindly
A fix can become expensive if prices fall and the exit fee makes switching painful.
Sources and useful links
Fixed vs Variable energy tariff — what changes
UK households can choose between fixing energy unit rates for 12-24 months or staying on the Ofgem price cap. Each has clear trade-offs.
Figures use 2026/27 UK tax-year rates and thresholds. Verify your specific situation against HMRC, FCA or MoneyHelper guidance before deciding.
Worked examples — see the math on real numbers
How fixed and variable energy tariffs compare in 2026, including the Ofgem price cap dynamics.
Cautious household — fixed-tariff preference
| Annual electricity | 2,700 kWh |
| Annual gas | 11,500 kWh |
| Current variable (cap) | £1,720/year |
| 12-month fixed deal | £1,650/year (£70 saving) |
| Risk of cap rising in next 12 months | Moderate |
The math:
- Fixed tariff saves £70 if cap stays at current level
- If cap rises 5% (£86 increase): fixed protects → £86 additional saving
- If cap falls 5% (£86 decrease): fixed costs £16 vs cap
- Historical pattern: cap moves quarterly, average move <5%
- Decision: fixed wins more often than variable but not by huge margins
Result: For risk-averse households, fixed at a small discount makes sense — peace of mind plus modest savings. Switching at the right moment (after a cap announcement) gets the best fixed rates.
Flexible household with solar + EV
| Annual usage | 7,500 kWh electricity (all-electric, EV) |
| Variable cap rate | ~28p/kWh standard |
| Octopus Agile half-hourly rate | ~17p average for someone with time-shifted usage |
| Savings via time-shifting | ~£800/year vs cap rate |
The math:
- Half-hourly variable tariffs reward off-peak usage
- EV night charging at 7-10p/kWh vs day rate 28p/kWh
- Heat pump pre-heat overnight vs daytime running
- Net saving over typical fixed tariff: £400-£800/year
- Required: smart meter + IHD + behavioural adjustment
Result: For EV + heat pump households, time-of-use variable tariffs are dramatically cheaper than fixed — typically £400-£800/year extra savings. For traditional gas+electric homes with no time-shifting opportunity, fixed-rate or default cap is usually fine.
Figures use 2026/27 UK tax-year rates and thresholds. Always verify against your specific payslip or tax statement before acting.
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