Taxpayers are being urged to check if they have overpaid income tax, following reports that around half a million people tried to claim refunds.
A Freedom of Information request submitted by Royal London showed that around 460,000 people have chased HMRC for income tax rebates.
In response, the Revenue said that people who changed jobs or were subject to changes to taxable benefits may have been overtaxed.
Those who received interest as part of payment protection insurance (PPI) compensation payouts have also paid more income tax than they should.
PPI payouts include annual interest of 8% to compensate claimants who were mis-sold the policies between in the 1990s and 2000s.
Becky O'Connor, personal finance specialist at Royal London, said:
"It's a good idea not to assume the taxman is always right about what he says you owe.
"Always check your tax statement for the year and keep a note of any unusual changes to your income that might mean you have overpaid.
"If you have received a payout for PPI compensation, it is worth checking the statement for details of any tax paid on the interest of your refund.
"If it was and tax was not due because the interest income was within your personal allowance or you are a non-taxpayer, you may be entitled to a refund."
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