A record 10.7 million self-assessment tax returns were filed before the 31 January 2018 deadline, according to figures published by HMRC.
Of around 11.4 million people who were required to submit tax returns for the year 2016/17, 93.5% successfully met the midnight deadline.
However, many returns were left late, with over 4.8 million people submitting their returns online in January alone.
More than a quarter of these were filed during the last 2 days of the month.
A total of 745,588 people missed the tax return deadline, and will face an initial fine of £100.
If the return is still not submitted after 3 months, this can rise to an extra £10 a day up to a maximum of £900, with additional penalties beyond 6 and 12 months.
Angela MacDonald, director-general for customer services at HMRC, said:
“It’s really fantastic to see that each year, more and more self-assessment customers are getting ahead of the game and submitting their tax return before the 31 January deadline.
“But we’re not complacent, we want the number missing the deadline to be zero, and we’ll continue to adapt the process.”