Millions of households have been urged to check their rights after an alert from the energy regulator.

Ofgem has issued fresh guidance reminding customers that strict rules are in place ‘to protect you’ from being charged for older energy use in many circumstances, following concerns that some households continue to receive unexpected demands. A back bill is sent when a gas or electricity supplier has failed to charge a customer correctly, often because of a billing error or problems with a meter.

While customers must pay an accurate bill, Ofgem says suppliers are generally barred from charging for energy used more than 12 months ago if the customer was not previously billed correctly or informed about what they owed.

Who is protected?

Under Ofgem’s back-billing rules, households normally do not have to pay for energy consumed more than a year ago if:

• they have never received an accurate bill for that energy
• they have not previously been told what they owed through a statement of account
• their Direct Debit had been set too low because of the supplier’s mistake.

However, the protection does not apply if a customer has “acted unreasonably” – for example by preventing meter readings, repeatedly ignoring requests for information or payment, or stealing gas or electricity.

Martin Lewis calls for tougher rules

The latest reminder comes after consumer champion Martin Lewis told MPs the current protections are not going far enough. Giving evidence to Parliament’s Energy Security Committee earlier this year, Mr Lewis said thousands of consumers were still receiving bills they should not have to pay, despite the existing rules.

He argued that the definition of customers who have “unreasonably obstructed” suppliers is too vague, making it easier for firms to dispute complaints. He also urged Ofgem to require suppliers to clearly explain customers’ rights whenever a back bill is issued.

Mr Lewis also said the 12-month limit should be cut to six months, telling MPs: “We live in a modern digital age… Why should a firm take over six months to give you a correct bill? I can’t see any reason for that.”

What to do if you receive a back bill

Ofgem says anyone who receives a back bill should first check whether the supplier has followed the rules. If you believe the demand covers energy that falls outside the permitted period, you should contact your supplier immediately. If the supplier has taken money in error, it should refund it.

Consumers struggling to pay, or who believe they should not have received the bill at all, are also encouraged to contact their supplier as soon as possible. If the dispute cannot be resolved, customers can make a formal complaint.

The regulator also says extra support may be available for households worried about paying their energy bills. More details here.