Self Assessment deadline January 2027: HMRC urges early start

HMRC is asking Self Assessment customers to begin their returns now rather than leave them until the new year. The Self Assessment deadline for January 2027 is 31 January for the 2025 to 2026 tax year.

The message came in an update published on GOV.UK on Thursday 8 October. It was timed ahead of World Mental Health Day on 10 October, and it comes with a survey: HMRC said an HMRC-commissioned survey of more than 5,200 customers found over 26% experience anxiety when tax or financial deadlines approach.

What the Self Assessment tax return deadline 2027 means

There are two dates that matter for most people. Online returns, and payment of any tax owed, are both due by 31 January 2027. Anyone who files on paper has a much earlier cut-off of 31 October 2026, which the Manchester Evening News noted is now only weeks away.

A third date helps some people. HMRC said Self Assessment customers with a PAYE income can file online before 30 December and have any tax owed collected through their tax code, rather than paying a lump sum. Customers signed up to Making Tax Digital for Income Tax still need to file and pay by 31 January 2027.

Myrtle Lloyd, HMRC’s Chief Customer Officer, said: “Self Assessment doesn’t need to be overwhelming, by starting early you have time to prepare properly and complete your tax return in manageable bitesize chunks, which is always better.” HMRC added that millions of customers already file well ahead of January each year, and that more than 24,000 filed on World Mental Health Day last year.

Who pays more if they leave it late

The cost falls on anyone who misses the deadline. According to the Manchester Evening News and the Daily Express, which both summarised HMRC’s guidance, failing to file by 31 January brings a fixed £100 late filing penalty, even if there is no tax to pay. After three months, a further penalty of £10 a day applies, up to a maximum of £900.

The charges keep building. After six months, there is an extra penalty of 5% of the tax due or £300, whichever is higher, and after 12 months another 5% or £300 is added. Interest is also charged on any tax left unpaid, on top of the penalties.

Filing early does not by itself cost less tax, but HMRC says an accurate return means you will not pay more than you need to. An early return also shows you what you owe while there is still time to plan how to pay.

A worked example: what a late return costs

Take two people who each miss the deadline entirely and leave both the return and the bill outstanding. One owes £4,000 and the other £8,000. Using the penalty rates HMRC has published, and counting only the penalties, not interest, the totals build as follows.

For the £4,000 bill, 5% is £200, so the £300 minimum applies. For the £8,000 bill, 5% is £400, which is higher than £300. The figures are our own arithmetic from HMRC’s published rates, not an HMRC estimate, and interest would come on top.

Someone who files in good time but cannot pay in full faces a different position. HMRC says you can set up a payment plan if you do not think you can pay on time, and filing early gives you longer to arrange one.

How to avoid the Self Assessment rush in 2027: what to do now

HMRC’s own tips are simple. Gather your records and personal income details before you start, then begin the return, save it and come back to it as often as you need. HMRC says taking breaks makes the process more manageable.

Budget is the fourth tip. HMRC suggests planning how you would like to pay what you owe, for example in monthly instalments, rather than facing a large bill all at once. In practice, that means working out your likely bill in October or November and setting money aside, instead of discovering the figure in late January.

If you are unsure whether you need to file at all, HMRC has a Self Assessment checker tool on GOV.UK. The same tool lets you register and tell HMRC if you no longer need to complete a return. Two further changes are worth checking for this tax year. HMRC said the 2025 to 2026 Winter Fuel Payment will be pre-populated in online returns where possible, and you should add it manually if it is missing. People with total income over £35,000 repay it through their Self Assessment bill. For those who pay the High Income Child Benefit Charge through Self Assessment, around 300,000 will now see Child Benefit details pre-populated.

Your questions answered

Who has to send a tax return?

According to the guidance reported by the Manchester Evening News, you must file if, in the tax year from 6 April to 5 April, you were a self-employed sole trader earning more than £1,000 before reliefs, or a partner in a business partnership. You must also file if you paid Capital Gains Tax on something you sold, or had to pay the High Income Child Benefit Charge without paying it through PAYE. Off-payroll workers repaying a student or postgraduate loan are included.

You may also need to file if you have untaxed income such as rental income, tips and commission, savings interest, dividends or foreign income. If you are unsure, use the HMRC checker tool on GOV.UK.

Can I file before January?

Yes. HMRC says you can send your return any time after 5 April, and doing so lets you find out what you owe, budget for weekly or monthly payments and have time to pay by 31 January. The paper deadline is earlier, so check which route you are using.

What if I cannot pay the full bill by 31 January?

HMRC says you can set up a payment plan if you do not think you can pay on time. The reported guidance also says interest is charged on tax that remains unpaid after the deadline. Anyone struggling with their mental health is advised by HMRC to contact NHS 111 or a mental health charity.