Martin Lewis warns Octopus, British Gas and EDF customers as millions owed hundreds in credit

It's been a busy week for the nation's financial expert, with the government's Autumn Budget setting out the UK's economic future.

But the work doesn't stop there for Martin Lewis, who has an important message for anyone who has an account with any of the major gas and electric providers, such as Octopus, EDF and British Gas.

The Money Saving Expert warned these energy companies are sitting on over £3 billion of customers' cash, and while some of it should be there, lots of it is for the taking, with this time of year dubbed the 'perfect' time to see if you're owed credit.

It all comes down to a little something called the energy Direct Debit cycle: most people find themselves in credit on their energy account during the summer, then use it all and often end up in a deficit in winter, and so on.

It's all about the energy Direct Debt cycle (Getty Stock Images)

Speaking on the Martin Lewis Money Show on ITV, he explained that most people should be in maximum credit by the end of November, but this credit should amount to no more than two months' worth of direct debits.

For example, if your monthly energy direct debit is £200, but you have £750 sitting in credit in your account, according to the financial journalist's theory, you should be able to safely withdraw £350, leaving £400 for the next two months' energy bills.

As for why November is the 'perfect time of the year', Lewis says you'll want to get the excess back, which you can request from the firm.

However, if you pay when you get a bill, then you'll often be charged 8 per cent more, but if you prefer that method, he suggests asking for 'variable Direct Debt', which is based on what you've used that month and taken out by Direct Debt instead.

On MoneySavingExpert.com, Lewis adds that some companies may not offer this, and you should still budget for your winter bills.

How to claim your energy credit back

If you decide you want to claim some of your energy credit back, the first thing you'll need to do is provide an accurate meter reading to ensure your direct debit payments accurately reflect your usage.

Once these readings have been submitted, you might find that the amount of credit in your account increases or decreases.

However, once the amount has been finalised, you can log in, and with most companies, there will be an option on your account to withdraw some of the credit.

If that option isn't there for you or you can't find it, you can call your supplier and request a refund over the phone.

It's important to note that some suppliers may require a minimum balance in your account before you request a refund, so check with your supplier to confirm their specific rules.