Self Assessment deadline 2027: 31 January and every other date

The main Self Assessment deadline is 31 January 2027. By then you need to file your 2025/26 tax return online and pay any tax you still owe for that year. The 2025/26 tax year ran from 6 April 2025 to 5 April 2026, so this is the return for the year that has already finished.

There is not just one date, though. Registration, paper returns and payments on account each have their own deadline. The table below sets them out in order.

You can see all the year’s dates, including VAT and company deadlines, on our tax deadlines page.

If you need a tax return for the first time, you must tell HMRC by 5 October after the end of the tax year. For 2025/26 that date was 5 October 2026. This applies if, for example, you started working for yourself or began letting a property during 2025/26.

Once you register, HMRC sends you a Unique Taxpayer Reference (UTR), a 10-digit number that identifies you for Self Assessment. You need it before you can file. It comes by post and can take a while, so register as soon as you can if you have not yet done so.

Not sure if you need to register at all? Our guide on whether you need to do a Self Assessment covers who has to file and how to sign up.

Payments on account are advance payments towards next year’s tax bill. HMRC asks for them so that self-employed people and landlords pay tax through the year, a bit like employees do through PAYE. Each payment is usually half of last year’s bill, and they are due on 31 January and 31 July.

They include income tax and Class 4 National Insurance (the National Insurance self-employed people pay on profits). You do not have to make payments on account if either of these applies:

• Your last Self Assessment bill was under £1,000.
• More than 80% of last year’s tax was already paid at source, for example through PAYE on a salary or pension.

Once the tax year is over and your return is filed, any tax still owed after the two payments on account is the balancing payment. It is due on the following 31 January. If you paid too much on account, the difference is refunded or set against your next bill.

The first year you owe £1,000 or more is the one that catches people out, because the January payment includes a full year’s tax plus half of next year’s on top. Here is a simple, hypothetical example.

If your 2026/27 bill then turns out to be £7,000, you have already paid £6,000 towards it, so the balancing payment on 31 January 2028 is £1,000, plus the first payment on account for 2027/28.

If you know your income has dropped, you can ask HMRC to reduce your payments on account. Only do this if you are confident, because HMRC charges interest if you reduce them too far and end up underpaying.

A return filed even one day after 31 January 2027 gets an automatic £100 penalty, even if you owe no tax. The penalties then grow the longer the return is late, and there are separate penalties and interest for paying late.

Late payment penalties are 5% of the unpaid tax at 30 days, 6 months and 12 months, plus interest. Our full guide to Self Assessment penalties and appeals explains how these add up and when you can appeal.

October and November are the best months to start. You have time to find missing paperwork, you know what you owe well before January, and you can plan for the payment rather than find it at short notice.

1. 1

   Check you can log in

   Make sure you have your UTR and can sign in to your HMRC online account. Sorting out access in January, when HMRC is busiest, is slow.

2. 2

   Gather your records for 6 April 2025 to 5 April 2026

   Sales invoices, bank statements, receipts for expenses, rent statements, P60s or P45s from any jobs, and details of interest or dividends.

3. 3

   Work out your profit

   Total your income, take off allowable expenses, and check you have not missed costs you can claim. Our self-employed tax calculator gives a quick estimate.

4. 4

   Work out what you will pay in January

   Remember to add the first payment on account for 2026/27 to the balancing payment. Set the money aside now.

5. 5

   File early, pay on time

   You can file any time before 31 January 2027. Filing early does not mean paying early: the payment is still due on 31 January.

Yes. We prepare and file returns for sole traders, landlords and company directors, check what you can claim, and tell you exactly what to pay and when. Our Self Assessment tax return service is on a fixed monthly fee from £99, with the price confirmed in writing before we start.

If you would like your 2025/26 return off your mind well before January, send us a quick enquiry and we will book a free 20-minute chat.