One million taxpayers face a penalty of £100 for failing to submit their self-assessment tax returns on time.
But the figure is the lowest since they were allowed to file online, comparing to 1.4m last year and 1.6m the year before.
The tax office, HMRC, allowed an extra two days' grace beyond the 31st January deadline because of a strike, but the 1 million had still failed to file by midnight last night.
They will have to pay the £100 fine whether or not they have additional tax to pay unless they have a reasonable excuse, such as a serious illness, a bereavement or a loss of documents because of theft, fire or flood.
After three months additional fines of £10 a day will start to accrue.
Self-assessment tax forms have to be filled in by people with more complicated tax affairs - for instance the self-employed or those with a high income from savings. The latest forms were for the tax year which ended in April, 2011.
A record 9.45m forms arrived by last night and 7.65m were submitted online - another record.