Around 10 million households have been urged to send their energy meter readings to their supplier as cheaper prices come into effect.
The average household energy bill fell 7% on Monday after Ofgem lowered its price cap in response to wholesale prices.
The regulator lowered the limit from £1,690 previously to £1,568 for a typical dual-fuel household in England, Scotland and Wales. This is a reduction of £122 over one year.
This is around £500 less than last July's limit of £2,074.
However, households on a standard variable rate rather than a fixed rate plan that do not have a smart meter will need to submit their electricity and gas readings to their supplier as close as possible to 1 July to ensure they are billed accurately at the lower rate.
Those who do not submit readings risk having some usage after this date billed at the previous, higher rates.
Suppliers who don't get meter readings bill based on estimated usage, meaning some households pay too much, while others pay too little.
According to calculations by comparison site Uswitch, the average household is expected to spend £83 on energy in July, up from £127 in June, as hot weather lowers limits and reduces usage.
The recent fall provides additional relief to households given the previous quarterly decline seen in April, but analysts said they expected Ofgem to raise the price cap in October before cutting it again in January 2025.
Uswitch has also urged households to look into other tariffs, including fixed deals, to help beat the expected October price rise.
Ben Gallizzi, Energy Spokesperson at Uswitch, said: “There are currently a number of fixed tariffs worth considering. If you choose a fixed deal, your rate will be locked in for that period of time (usually 12 months). “This means households have price certainty and can avoid fluctuations in price ceilings.”