Over 93% of taxpayers filed their self assessment tax returns by the deadline; however, 700,000 taxpayers have yet to comply.
More than 11.5 million taxpayers were required to file their 2017/18 tax returns by 11.59pm on 31 January. The majority filed on time, but 700,000 taxpayers missed the deadline, according to HMRC.
More than 700,000 taxpayers submitted their tax returns on deadline day; the peak hour for filing was between 4pm and 5pm when 60,000 filed. The number of taxpayers who filed online rose to more than 10.1 million for the first time.
Angela MacDonald, HMRC's director general for customer services, said: "Thank you to everyone who filed on time. This year, we had a record number of filers completing their tax returns by the deadline. And for any customers who are yet to file their returns, please contact HMRC - we are here to help."
HMRC says it will treat those with genuine excuses leniently, as it focuses penalties on deliberate tax evaders and those who persistently fail to complete their tax returns. However, any excuse given must be genuine and HMRC may ask for evidence.
The penalties for late tax returns start with an initial £100 fixed penalty, which applies even if there is no tax to pay, or if the tax due is paid on time. Penalties rise as time goes by.
The Federation of Small Businesses (FSB) has urged HMRC to exercise leniency towards sole traders who submit returns late or incorrectly. Over the past year, it says, HMRC's engagement with the self-employed has been "dogged by inaccurate reminders and penalty notices, phishing emails, poor customer service and an unreliable tool for assessing employment status".
The latest HMRC statistics show that one in five callers to HMRC's helpline are left waiting more than ten minutes to speak to an advisor. "HMRC's performance over the past year has been nothing short of calamitous," said Mike Cherry, FSB national chairman.
"From premature late penalty notices, to misleading demands for payment, to increasing call waiting times, the self-employed are being let down time and again by this increasingly ill-equipped agency."
HMRC, he said "must remember that the self-employed are specialists injecting much-needed expertise and flexibility into our economy. The vast majority are not tax specialists - and they don't have time for hold music."