Martin Lewis issued an urgent warning to homeowners who may have lost thousands.
Following the expense of Christmas, the financial guru offered some helpful advice on his money saving show.
One of the main topics of concern for viewers was council tax bands.
Martin revealed that over 400,000 homes are believed to be in the wrong bands, meaning every year homeowners are paying more than they should.
This included one man, who disclosed to Martin that he'd been in the wrong tax band since the 1980s.
The man told Martin that he had only recently realised his band was higher than his neighbours - meaning he'd paid an extra £4,680 than he needed too.
He managed to get the money back after taking Martin's advice on board.
Martin told viewers that it only takes 10 minutes to check and challenge your council tax banding, potentially slashing what you pay now and getting a rebate going back years.
How to check your band
If you're in England, Gov.uk will explain how to challenge your council tax band.
You can either contact the Valuation Office Agency (VOA) directly, at which point you'll be told how your band was decided, and be able to challenge your band.
You can also check your band by entering your postcode and selecting your address from a list. Then you can click on the link asking if you think your council tax banding is wrong and you'll be given the option to fill out a checklist which suggests reasons you could challenge.
You can read more on MoneySavingExpert.com.
