Taxpayers are being given just days to pay bills totalling thousands of pounds in the latest clampdown by HM Revenue & Customs.
Many of those being sent demands are pensioners on low incomes who had been told they would have more than a year to pay back the tax they owed.
Those with the largest bills believed they could have up to three years, the Money Mail reports, but instead they are being given just a month to pay the bill.
Most of those affected are among the 1.4 million sent tax demands totalling £3.8bn after HMRC admitted last September it had got millions of tax bills wrong.
According to the Mail, one pensioner was sent a letter on February 4 saying they must pay £2,865.20 by March 5. In another case, a 66-year-old man was told on February 18 he needed to find £1,413.58 by March 21.
Others, who owe nothing, have still been sent demands and some who dispute their bill have been sent an even bigger one.
In one case, a 73-year- old from Harrogate, who contested a tax bill of £3,000 for the years 2008 to 2010, was sent a further demand for 2007/08.
Some are still involved in battles with HMRC to try to find out precisely why they owe money. They argue that HMRC knew all the details of their tax affairs, and so is not entitled to ask for money back.
Others have cited a loophole called Extra-Statutory Concession A19, which allows them to have their debts written off. This applies to those people who believed their tax affairs were in order and can prove that HMRC knew about all their income yet still failed to charge them the right amount of tax, Money Mail reports.
The latest figures reveal 37,174 people have applied for a concession, of whom 10,175 have been successful.
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