Taxpayers who haven't yet submitted their self-assessment return for the previous tax year are being warned they could incur an initial £100 penalty after Saturday night. This year's cut-off point is the close of the day tomorrow, January 31.

In a post on X on Thursday, HMRC reminded individuals that a tax return is required if they have generated more than £1,000 from a side business, are self-employed, let out a property or engage with cryptoassets. It relates to the 2024-25 tax year.

Last week, Myrtle Lloyd, HMRC's chief customer officer, advised: "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. If you're worried about paying your tax bill, you may be able to set up a payment plan online – search 'difficulties paying HMRC' on gov.uk."

This year's cut-off date lands on a Saturday. HMRC's telephone lines operate Monday to Friday between 8am and 6pm.

Telephone services will shut on Friday, January 30, and resume on Monday, February 2 – following the deadline. HMRC confirmed it will provide webchat assistance on Saturday, January 31, via its online services helpdesk.

HMRC self-assessment deadline 'time running out'

Alastair Douglas from Totally Money warned: "Time is quickly running out for anybody who still needs to file their self-assessment return, and if you don't get it in, or pay your bill before midnight on Saturday, the taxman will penalise you. For late filing, you'll receive an initial £100 penalty, and after three months, you'll be charged an extra £10 every day. For late payment, you'll be charged 5% of the unpaid tax after 30 days, six months and again after a year – and you'll be charged interest on what is owed."

He added: "If you can't afford to pay the full amount, then contact HMRC to set up a payment plan. All you'll need is your Unique Tax Reference number, bank details to set up a Direct Debit, and details of your income and expenses. This can be done online, or over the phone on 0300 200 3822 – but remember that their phone lines are only open on weekdays between 8am and 6pm."