Last reviewed 24 January 2019

More than 3.5 million people have just one week left to complete their self-assessment tax returns and pay any tax owed, HM Revenue & Customs (HMRC) is warning.

The deadline to complete a 2017/18 tax return online is 11.59pm on 31 January. An extra 25,000 customers have already filed their self-assessment, compared to this time last year, but there are 3,500,813 returns still to file, as of 23 January 2019 (compared to 3,524,798 as at 23 January 2018).

In total, HMRC calculates 11,564,363 self-assessment returns are due, of which it has so far received 8,063,550 (70%).

Of these, 91% were filed online totalling 7,359,607 returns, with just 703,943 returns filed on paper for the earlier October deadline.

HMRC is reminding taxpayers that if their tax return is late, they will receive a £100 penalty — even if they do not owe any tax. Last year around 93% of individuals hit the 31 January date.

Mel Stride, financial secretary to the Treasury, said: “The deadline for the self-assessment tax return is fast approaching but there is still time for the 3.5m customers who haven’t completed their return to file by 31 January.

”With only seven days to go it is important that customers are reminded of the self-assessment deadline in order to avoid paying penalties.”

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.

This is followed after three months by, additional daily penalties of £10 per day, up to a maximum of £900; after six months, a further penalty of 5% of the tax due or £300, whichever is greater; and after 12 months, another 5% or £300 charge, whichever is greater.

There are also additional penalties for paying late of 5% of the tax unpaid at 30 days, six months and 12 months.

Self-assessment guidance is available here.

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