The key Self Assessment dates for 2026 and 2027
The UK tax year runs from 6 April to 5 April. The return you file in 2026 and early 2027 covers the 2025/26 tax year, which ended on 5 April 2026. HMRC's Self Assessment deadlines page sets these dates, all at 11:59pm unless stated.
| Date | What is due |
|---|---|
| 5 October 2026 | Tell HMRC you need to file for 2025/26, if you have not filed before (register for Self Assessment) |
| 31 October 2026 | Paper tax return for 2025/26 must reach HMRC |
| 30 December 2026 | Online return, if you want the tax collected through your PAYE tax code (conditions apply) |
| 31 January 2027 | Online tax return for 2025/26 |
| 31 January 2027 | Pay the balancing payment for 2025/26 and the first payment on account for 2026/27 |
| 31 July 2027 | Second payment on account for 2026/27 |
| 5 October 2027 | Register if you first need to file for 2026/27 |
| 31 October 2027 / 31 January 2028 | Paper / online return for 2026/27 |
The tax code option only works if you have PAYE income, such as a salary or pension, and HMRC agrees to collect the amount that way. HMRC's deadlines page sets the 30 December date; check HMRC's eligibility conditions before relying on this route.
If you register after 5 October, HMRC sends a letter or email with a different filing deadline, 3 months from the date on it. The tax is still due by 31 January 2027.
Registering by 5 October 2026
If you need to file for 2025/26 and have not filed before, you must tell HMRC by 5 October 2026. GOV.UK's registration page, updated 25 September 2026, warns that if you tell HMRC after that date "you could get a penalty". Registration gives you a Unique Taxpayer Reference (UTR), which HMRC usually posts around 15 days after you register, longer if you live abroad.
Common reasons to register include self-employment income over £1,000, rental income, dividends above your allowances, and untaxed foreign income. HMRC's page on who must send a tax return has the full list, and our UTR guide explains the number itself.
Paper or online: 31 October vs 31 January
Paper returns have a much earlier deadline. HMRC must receive a paper return by 31 October 2026; an online return has until 31 January 2027. A paper return that arrives after 31 October is late, even though an online return filed on the same day would not be.
Most people file online, either through HMRC's own online service or commercial software. If you still plan to file on paper, post it well before 31 October, because the date that counts is when HMRC receives it.
Paying: balancing payment and payments on account
31 January is both a filing and a payment deadline. On 31 January 2027 you pay:
- The balancing payment for 2025/26: the tax you owe for the year, minus any payments on account already made toward it.
- The first payment on account for 2026/27: half of your 2025/26 tax bill, paid in advance toward next year.
The second payment on account for 2026/27, the other half, is due on 31 July 2027. These rules come from HMRC's guide to payments on account, which includes Class 4 National Insurance for the self-employed.
When payments on account do not apply
You do not make payments on account if your last Self Assessment bill was under £1,000, or if more than 80% of your tax was collected at source, for example through PAYE on a salary.
A worked example
Say your 2025/26 bill is £4,000 and it is your first year, so you made no payments on account toward it. On 31 January 2027 you pay the £4,000 plus a first payment on account for 2026/27 of £2,000, a total of £6,000. On 31 July 2027 you pay another £2,000. When you file for 2026/27, the £4,000 already paid is deducted from that year's bill. This first-year jump catches many new sole traders, so set money aside early.
Reducing payments on account
If you expect lower income, you can ask HMRC to reduce your payments on account online or on form SA303. HMRC warns that if you reduce them and your bill turns out higher, "you'll be charged interest on the difference".
Penalties for late returns
Penalties apply even if you owe no tax. HMRC's Self Assessment penalties page sets the late filing scale:
| How late the return is | Penalty |
|---|---|
| 1 day | £100 |
| 3 months | £10 a day, up to a maximum of £900 |
| 6 months | A further 5% of the tax due or £300, whichever is greater |
| 12 months | Another 5% of the tax due or £300, whichever is greater |
So a return filed 6 months late with little tax due already costs £100 + £900 + £300 = £1,300.
Penalties and interest for late payment
Late payment penalties are 5% of the tax unpaid at 30 days, 6 months and 12 months after the due date, again from HMRC's penalties page.
Interest is separate and is charged on tax paid late until it is paid. HMRC's late payment interest rate for Income Tax has been set at Bank of England base rate plus 4% since 6 April 2025, so the percentage moves whenever the base rate changes. Check HMRC's rates page for the current figure.
You can appeal a penalty if you have a reasonable excuse for missing the deadline. HMRC's penalties page links to the appeal route and to a tool that estimates penalties for late returns and payments.
How Making Tax Digital for Income Tax changes things from April 2026
Making Tax Digital (MTD) for Income Tax started on 6 April 2026 for sole traders and landlords with qualifying income over £50,000, based on their 2024/25 return. The threshold falls to over £30,000 from 6 April 2027 and over £20,000 from 6 April 2028, according to HMRC's MTD eligibility guidance. For people in scope, it adds deadlines on top of the annual ones:
- Quarterly updates from compatible software, due 7 August, 7 November, 7 February and 7 May for the standard quarters.
- The tax return still goes in by 31 January after the tax year. For 2026/27, the first MTD year, that is 31 January 2028.
- Payment dates do not change. Balancing payments and payments on account keep their 31 January and 31 July dates.
Which penalty rules apply to which return
MTD brings a new penalty system, but only from the year you join. HMRC's MTD penalties guidance says the new penalties "will apply to you from the tax year you join" and "current penalties will still apply to previous tax years". So your 2025/26 return, due 31 January 2027, is still under the penalty scale above, even if you joined MTD in April 2026.
For 2026/27 onward, MTD users face points-based late submission penalties: a point for each missed deadline and a £200 penalty at 4 points. HMRC says there are no penalties for missed quarterly updates in 2026/27. Late payment penalties change to 3% of the tax owed at day 15 and another 3% at day 30 for 2026/27 (4% each from 2027/28), plus a yearly rate of 10% charged daily from day 31. In your first year there is no penalty for paying 16 to 30 days late.
Your 2025/26 return matters for next year too. HMRC uses it to decide whether you must join MTD from 6 April 2027 at the £30,000 level, so check your qualifying income when you file.
Our Making Tax Digital for Income Tax guide covers qualifying income, software, exemptions and quarterly updates in detail.
Filing from outside the UK
Living abroad does not change the dates. Non-residents with UK income, such as UK rent or UK self-employment, file on the same deadlines. Post takes longer, so register early to allow for your UTR letter to arrive, and send international payments with enough time to clear before 31 January. Whether you are UK resident for tax is a separate question from these dates; if it is unclear, get advice before you file.
Getting it filed on time
You can file for free through HMRC's online service. Borderless Filings prepares and submits Self Assessment returns from your uploaded records: we check your income and payments on account, send you the calculation to approve, file the return, and remind you of 31 January and 31 July payments. We are a filing service, not a tax adviser, so questions about residence or treaty relief go to a qualified professional. See our Self Assessment tax return service, or check your company and personal dates in the compliance deadline calendar.
Sources
- GOV.UK: Self Assessment tax returns, deadlines
- GOV.UK: Register for Self Assessment
- GOV.UK: Who must send a tax return
- GOV.UK: Find your UTR number
- GOV.UK: Payments on account
- GOV.UK: Self Assessment tax returns, penalties
- HMRC: Rates and allowances, HMRC interest rates
- HMRC: Find out if and when you need to use Making Tax Digital for Income Tax
- HMRC: Use Making Tax Digital for Income Tax, send quarterly updates
- HMRC: Penalties for Making Tax Digital for Income Tax
Fees, deadlines and rules on this page were last checked on 27 September 2026.