Filing an annual tax return is irksome at the best of times. But for elderly people who may in any case have very little tax to pay, the process is a burden.

Official figures show 1.7 million pensioners are still required to file a return. Of those pensioners 275,000 are over the age of 80, according to a Freedom of Information response obtained by mutual insurer Royal London.

Self-assessment tax returns are filled out by those who do not satisfy the standard criteria for pay-as-you-earn (PAYE) taxable income, such as those who are self-employed. Pensioners will be liable to fill one in if they continue working on an ad-hoc basis or have another source of income, such as rent or dividends.

Around 27,000 people receiving the state pension also need to fill in a return as the amount they receive is above the personal allowance of £11,500. The elderly represent a growing portion of income taxpayers, and pensioners now account for 21pc of the 30m eligible to pay in Britain, up from just 12pc in 1990.