Households have been urged to take their energy meter readings – and try to submit them – ahead of prices rising from October 1.
This will prevent firms from estimating usage and charging for energy used before October 1 but at the higher rate.
The average household energy bill will rise from £1,971 to a frozen £2,500 under the energy price guarantee announced by Prime Minister Liz Truss earlier this month. This is an increase of 27% from the previous price cap, which limited the rate providers can charge customers on a standard variable tariff.