How do I get the money?
All customers with a domestic electricity meter who pay by direct debit, either monthly or quarterly, or by card will see an automatic deduction off their bills.
Those with "smart" prepayment devices will see an automatic monthly top-up added to their account, meaning they will have to add less credit to their meter for the total energy they use.
The government has announced how all households in England, Scotland and Wales will receive £400 to help with rising fuel bills this autumn.
The money, part of the Energy Bill Support Scheme, will be paid in six instalments.
Households will see a discount of £66 applied to their energy bills in October and November, and £67 a month from December to March 2023.
But how the money is received will depend on how you pay your bill.
But those with older "non-smart" prepayment devices will not get this money automatically.
Instead, they will receive an energy bill discount voucher in the first week of each month, via text, email or in the post. Customers will have to redeem these in person at their usual top-up point, such as a local Post Office.
"While no government can control global gas prices, we have a responsibility to step in where we can and this significant £400 discount on energy bills we're providing will go some way to help millions of families over the colder months," said Business Secretary Kwasi Kwarteng.
The energy price cap - the maximum amount suppliers can charge customers in England, Scotland and Wales - is expected to go up in October. In May, energy regulator Ofgem said the typical household should expect to see an £800 increase in October, to £2,800 a year.
However, one industry analyst, Cornwall Insight, has estimated that the typical domestic customer is likely to pay £3,244 a year from October, then £3,363 a year from January.
More than four million households use prepayment meters in Britain, according to Ofgem. Less than half of those meters - 1.9 million - are smart devices that will allow this payment to be made quickly and easily.
Charities are concerned that for the more than two million households with traditional non-smart prepayment devices - often the most vulnerable and poor in society - this energy help will be harder to access.