With less than a week until the self assessment deadline, 8.6m people have already filed their return for the 2024 to 2025 tax year, HMRC reports.
It is urging taxpayers and agents who haven’t filed, to act now or risk missing the 31 January deadline – and face an automatic £100 penalty.
More than 11.5m customers successfully filed by the deadline last year and HMRC said it wants to help the 3.3m still outstanding this time around to do the same.
This year's deadline falls on a Saturday. Customers who need to speak to an adviser can call HMRC's phone lines, which are open Monday to Friday, 8am to 6pm. Phone lines close on Friday 30 January and reopen on Monday 2 February – after the deadline.
For full phone support, HMRC advises people to contact it before Friday 30 January. On Saturday 31 January, HMRC will offer webchat support through its Online Services Helpdesk.
Myrtle Lloyd, HMRC's chief customer officer, said: "Don't leave it until deadline day. Filing now will give you peace of mind that your tax return is completed and if you have tax to pay, you have a week to arrange payment.”
She said people worried about paying their tax bill, may be able to set up a payment plan online.
The penalties for late tax returns are:
• an initial £100 fixed penalty, which applies even if there is no tax to pay, or if the tax due is paid on time
• after 3 months, additional daily penalties of £10 per day, up to a maximum of £900
• after 6 months, a further penalty of 5% of the tax due or £300, whichever is greater
• after 12 months, another 5% or £300 charge, whichever is greater
There are also additional penalties for paying late. Penalties will be charged at 5% of the tax unpaid at 30 days, 6 months and 12 months. If tax remains unpaid after the deadline, interest will also be charged on the amount owed, in addition to the penalties above.
HMRC said it will consider customers' reasons for missing the deadline. Those with a reasonable excuse may avoid a penalty.
Sole traders and landlords with qualifying income of more than £50,000 will be required to use Making Tax Digital (MTD) for Income Tax from 6 April 2026 and be required to submit quarterly summaries of their income and expenses to HMRC.