Income tax recalculations have meant that thousands of Britons will have to make extra repayments to the Inland Revenue.
Pensioners hit by the income tax code changes will not have to pay back any outstanding sums.
Thousands of UK workers may have to make extra income tax payments to HMRC due to a tax code recalculation.
A total of £180 million needs to be paid back by 450,000 people who had the wrong tax code between 2007-08. However, 250,000 state pensioners who underpaid during between 2008-09 will not have to pay back a penny.
Exchequer Secretary to the Treasury David Gauke said: "By the end of last year in 90% of cases where HMRC had received all relevant information, customers had received a refund notice or a calculation of overpayment in respect of these years".