Common reasons
- Seasonal changes — more lighting and heating in winter.
- Price changes when your tariff or the price cap changes.
- Estimated readings that are later corrected.
- Different billing period lengths.
- Direct debit amounts that are averaged across the year.
Checking your bill
Compare the kWh used and the number of days in each billing period. Then use the calculator with your unit rate and standing charge to see whether the total looks reasonable.