More than one million taxpayers face a penalty of £100 for failing to submit their self-assessment tax returns on time.
The figure of 1.1 million is the lowest since online filing first started, and compares with 1.4 million last year and 1.6 million the year before, reports the BBC.
HM Revenue and Customs allowed an extra two days' grace beyond the normal 31 January deadline due to strike action.
However, 1.1 million people failed to file by the end of 2 February.
They will have to pay the £100 fine unless they have a reasonable excuse.
Valid reasons include serious illness, a bereavement, or a loss of documents because of theft, fire or flood.
After three months, additional fines of £10 a day start to accrue and could eventually amount to a maximum of £1,600.
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