Moved house or switched energy supplier? Check if you're due a share of £240 million sitting in old energy accounts

While many will likely only find a few pounds, some could be owed more than £100 each, Ofgem says. The regulator adds that most of these balances are from the past five years, so you're less likely to be due if you moved or switched more than five years ago – though it's still worth checking just in case.

Why you may have credit in an old account

Usually, you don't need to do anything to claim any leftover credit – under Ofgem's rules, suppliers are required to issue a final bill within six weeks and then a refund within 10 working days of the account's closure. As a result, more than 90% of account balances are automatically returned to consumers, according to industry body Energy UK.

However, if your contact details changed – because you moved house, for example – and your supplier couldn't reach you, it may not have been able to issue the refund. This may also be the case if you cancelled your Direct Debit before your account was settled. In these cases, you'll need to act.

How to check and reclaim your credit

Here are the steps to follow:

1. Log in to your old online account to check the balance. If you're in credit, this should be shown in your account balance – often the first thing you see when you log in. The way this is displayed can vary between suppliers, but if it's anything other than £0.00, you may be owed – especially if the amount in pounds and pence is followed by the word 'credit' or the letters 'CR'.

If you didn't have an online account, can't remember the details, or can no longer log in, then...

2. Contact your old supplier directly (by calling or using its web chat, for example). Explain that you used to be a customer and you want to check if you have any credit left on your account. To help the firm find your account, you'll need to provide information including your name, address and contact details (and old account number, if you have it).

3. If there's credit left on the account, ask the supplier to refund it. You may need to give the supplier your up-to-date details so it can process the refund.

Can't remember which energy supplier you were with?

Here's what to try:

• Search your emails and texts. Look for energy bills or other correspondence from energy firms.

• Check your password manager or saved passwords in web browsers. If you had an online account with the firm, you may still have the password saved.

• Check your credit reports. These will show old addresses and may show some of your closed utility accounts (depending on the supplier). See how to check your credit report for free.

Beware scammers trying to take advantage

Ofgem ISN'T contacting energy customers directly about energy credit they may be owed. But fraudsters may use this as an opportunity to try and harvest your personal details – we've previously seen scammers impersonating Ofgem and the Government.

If you get a call, text or email out of the blue claiming to be from Ofgem, DON'T respond to it or click any links – it's likely a scam. Instead, find your old supplier's details independently (from an old bill or its official website, for example) and contact it directly. For more help and tips to avoid scams, see our 30+ ways to stop scams guide.