Taxpayers who have yet to complete their self-assessment tax return for the 2017/18 tax year have until midnight on 31 January 2019 to file it online - or face a fine.
People who are self-employed or have more than one source of income are usually required to complete a self-assessment tax return.
Last year, more than a quarter (26.6%) of all returns were submitted on 30 and 31 January, with 30,348 of those left until the last hour, between 11pm and 11.59pm.
However, 745,588 people missed the deadline and received fines of £100 or more for late filing.
Angela MacDonald, director-general for customer services at HMRC, said:
"We want the number missing the deadline to be zero.
"Please submit your return now to avoid further penalties. We really don't want [to be handing out] penalties, we just want tax returns."
Our team is working around the clock on your behalf to beat the midnight deadline, but other taxpayers will be taking on the task without professional help.
To complete your self-assessment return, you'll need your login information and up-to-date financial records from 2017/18 to hand.
Once you have completed the return, HMRC will calculate and send you the amount of tax due, which also needs to be paid by the 31 January deadline.
Get in touch to discuss self-assessment.