Martin Lewis, 45, has helped hundreds of people save money when it comes to their household bills.
People may not be aware how much they are being overcharged when seasons change or estimates are incorrect.
He has revealed on Good Morning Britain how, if you pay by direct debit, you could get hundreds of pounds back from your electricity or gas bills.
The expert explained: “If you’re one of around 70 per cent who pay electricity and/or gas bills by direct debit, check now if you’re due credit back.
“Pay by monthly direct debit and energy firms usually bill on an estimate of your usage. Yet estimates are often wrong, leaving some massively over- or underpaying.
Martin Lewis Money Saving Expert: Reclaim £100’s in energy credit
Homeowners tend to go into credit during the summer months thanks to less bill usage, which he explains helped for the winter months.
“As most direct debits aim to smooth out seasonal usage, you should’ve been in credit going into winter, and have no or a slight deficit by now, so this is the safest moment to judge if you’re overpaying,” he said.
“If you don’t give regular meter readings, then fix this first (unless you have a smart meter doing it for you) as you won’t know your actual usage. After you give a reading, ensure it’s factored into your bill before the next step.
“If you’re in credit by over a month’s direct debit (go online or call to find out), then politely request your provider repays any excess over that, as a month’s worth is a lot in spring.
“Energy firms’ licence conditions give you a right to fair direct debits – so if you have too much credit now, ask it to justify why (there may be a legit reason), and if it can’t, get it lowered.”
Martin Lewis: Money Saving Expert reveals how to get money back from energy bills
Martin also revealed it was the last change for people to shift their debt to a 0 per cent fee card for the next 25 months.
He said: “One to highlight right now, as the deal closes on Monday is that accepted new Barclaycard cardholders (do note it has many offers so make sure you get the right one) can shift debt to it for up to 25 months 0 per cent without the usual one off fee (in fact it does charge a 2per cent fee then refunds it within 28 days).
This isn’t far from the longest no fee 0 per cent deal on the market. Plus crucially it gives you £20 cashback (within 2 days) if you shift at least £1,000 to it within 60 days (though you can’t transfer a balance from another Barclaycard).
“In other words you’ll be paying no interest and have £20 less debt on the card that you started with – which for those who can clear their debts within the 0 per cent period is unbeatable.”
Martin Lewis: Energy bills could be cut
Other advice revealed how people can get a free £20 eye test voucher for Supersavers, available at over 300 stores, and how to using the eBay app can help sellers found out how much their stuff is worth.
The Money Saving Expert has also revealed how to avoid large energy bill hikes later this month.
British Gas are increasing gas and electricity costs on 29 May, adding £60 a year whilst EDF are to increase electric bills on 7 June, adding £16.
By switching to another provider, hundreds can be saved, as can coming off a standard tariff.
There is also no break in supply when switching, putting households at ease that they won’t be out of power.