Martin Lewis has clarified a key point for energy bill payers and reminded them that bills can only go back for a maximum of 12 months - anything before that should be written off, as long as customers were not notified previously.
The Money Saving Expert founder has hit out at gas and electricity firms who leave customers with higher bills thanks to faulty meters.
Earlier this year he appeared before the Energy Security and Net Zero Committee in the House of Commons to campaign on the key issue of back billing. Also known as a "catch-up bill", energy firms bill customers for energy that wasn't previously accounted for, usually because of gaps in meter readings.
Energy firms CANNOT bill you for energy used over 12mths ago. Yet many do. My evidence to Commons Energy Committee on this including how the rules should be changed. Please share so people know their rights. pic.twitter.com/oJM0sZX1Oi
— Martin Lewis (@MartinSLewis) March 20, 2025
The Money Saving Expert founder often shares his advice on X, and in a post he told billpayers: "Energy firms CANNOT bill you for energy used over 12mths ago. Yet many do. My evidence to Commons Energy Committee on this including how the rules should be changed.
"Please share so people know their rights."
Energy bill back billing rules
If your gas or electricity supplier believes you have not been accurately billed for energy you’ve used, they may send you a back bill.
These bills are sometimes called ‘catch up’ bills, and are intended to cover a period where you’ve used energy but have not been charged for it.
If you get one of these from your supplier, check whether you’re protected by Ofgem's back billing rules before deciding what to do next.
Energy firms AREN'T allowed to back-bill over 1 year Ie. if you're sent a bill for the first time about energy from past years (providing you didn't obstruct em in getting the info) it's usually wrong. You needn't pay it. Make a formal complaint & if needed go to Energy… pic.twitter.com/PNhKKsVyQ5
— Martin Lewis (@MartinSLewis) March 3, 2025
Ofgem back billing rules
You cannot be charged for energy used more than 12 months ago if:
Suppliers must make these rules clear in their contract terms and conditions.
The rules only apply to domestic energy consumers and microbusinesses.
What to do if you get a back bill from your energy supplier
Contact your supplier and let them know. They should refund any money taken in error, which could be all or part of the bill.
You’ll find your supplier’s contact details on their website, or on your energy bills.
If you want to write to them or send them an email, you can use the Citizens Advice back billing example letter.
You can complain about your energy supplier if they continue to ask for payment for a period covered by Ofgem's back billing rules.
The rules do not apply if you have acted unreasonably by:
Paying a back bill
You are responsible for paying for the energy you have used in any period not covered by the back billing rules.
If you’re worried about being able to pay, take a look at the help and support options available if you cannot afford your energy bills.
Recommended reading:
How to help make sure your energy bills are accurate
The best way to avoid getting a back bill is to make sure you receive regular, accurate bills from your supplier.
Make sure the bills you get accurately reflect the energy you’ve used. If you think there’s something wrong with your bill, for example, if you’ve been undercharged, contact your supplier right away.
You should also contact your supplier to let them know if you do not receive a bill for energy you’ve used.
If you do not have a smart meter, make sure to give your supplier regular meter readings.