Widespread tax error affects millions as one person overpays £9,400 to HMRC

Widespread tax error affects millions as one person overpays £9,400 to HMRCYou can check that your details with HMRC are correct in several waysCommentsMoneyNicholas Dawson14:27, 12 Apr 2026View 2 ImagesMillions of people are thought to be paying the wrong amount of tax(Image: Getty)Taxpayers are being urged to review their records as countless people have incorrect information registered with HMRC. Consumer website MoneySavingExpert (MSE), founded by Martin Lewis, has warned that millions need to update their details with the taxman.‌In a social media alert, the organisation said: "A new tax year means it's a good time to check your tax code. If it's wrong, you could be due £1,000s back." The message highlighted that "millions are wrong each year" and stressed that checking your tax code is correct is your personal responsibility.‌This means if you are in employment, it falls to you to ensure your code is correct, not your boss. The MSE team highlighted a success story from someone who'd clawed back a huge sum after being on an incorrect tax code for several years.‌Content cannot be displayed without consent£9,400 refund from HMRCThe taxpayer, called Michele, explained: "I was being taxed on every penny I earned, without any allowance. I'd previously been self-employed, but stopped trading three years ago and my tax code hadn't been updated with my employer."It took an hour on the phone to HMRC, but I've now been refunded £9,400." Your tax code dictates how much tax your employer or pension provider deducts from your income.‌You'll find yours on a recent wage slip or on a Tax Code Notice letter, should HMRC send you one. Everyone receives a standard tax-free allowance, enabling them to earn up to £12,570 per year without paying income tax on those earnings.View 2 ImagesYou may want to check your tax details are correct(Image: Getty)You could overpay thousandsHowever, if you're on an incorrec...