The Money Expert has urged users paying their energy and electricity bills by Direct Debit to check their credit.
Martin revealed on his ITV Money Show that energy providers are sitting on billions in consumer credit.
He said: “There are over £8 billion of credit sitting in firms bank accounts and some of it should be in your bank account.
“I’ve been nagging about it because it’s a lot of money saved up.”
Direct Debit users pay the same amount every month through summer and winter.
But usage cost can get higher in the winter when heating is turned on and lower in the summer.
Customers can reclaim their money back if they have overpaid months with less energy usage.
For this, the money-saving whizz is urging Brits to call their energy companies to receive the cash back.
He Brits should make sure their meter readings are up to date or have a working smart meter.
They should then go onto a direct debit calculator to make sure they’re paying roughly the right rate.
“What you want right now at this point in the cycle is two months old of energy credit,” he said.
On the program a user claimed she received a whopping £500 in refunds after being £728 in credit and paying £199 a month.
After claiming the money through a quick phone call, she said her energy provider will hand the cash back on her bank account in the next 10 working days.
It comes as Martin Lewis shared a two step method to “make serious money” without lifting a finger.
The Money Expert said the benefits begin when you check your cash ISA rate.
He also revealed the exact date to get a half-price Christmas dinner.
During an episode of The Martin Lewis Money Show on ITV the money guru gave a “Festive Forecaster” where he revealed when supermarkets will start to reduce their items.
If you want to get a “half-price Christmas Dinner” there is one date you should keep your eyes peeled for.
Martin said: “Christmas veg is likely to be reduced around Monday 12 December.
“I suspect there will be big Christmas veg deals coming when we get to that time of year.”
Cheap tricks for keeping warm this winter
There are a few tricks you can use to stay as warm as possible this winter.
If you’ve got a few pennies to spare consider buying an electric blanket.
They are another great way to keep warm and most cost around 3p an hour to run.
Don’t forget about preventative measures, draught-proof your home and seal your windows to stop air coming in.
Prices for draught excludes start from a fiver in most stores but a thick blanket rolled up will work just as well.
Loft insulation is also very important as it can stop heat escaping, therefore slashing your heating bill.
You can buy insulation from all local builder merchants or retailers such as B&Q and Wickes.
We’ve found five energy-saving gadgets to buy for winter that can cut bills by £1,259.
Find out the 13 best electric blankets to keep you warm at night this winter.
And the eight cheapest hot water bottles to buy now to avoid putting the heating on at night.