Self Assessment deadlines and payments on account, explained
Figures checked on gov.uk on 26 October 2026
The tax year runs from 6 April to 5 April. Your Self Assessment return for a tax year is due the following January, and so is the tax. These are the dates for the 2025 to 2026 tax year, which ended on 5 April 2026.
The deadlines
| What | Deadline |
|---|---|
| Tell HMRC you need to do a return, if you don’t already | 5 October 2026 |
| Paper tax return | 31 October 2026 |
| Online tax return | 31 January 2027 |
| Pay the tax you owe for 2025 to 2026 | 31 January 2027 |
| Second payment on account for 2026 to 2027 (if you make them) | 31 July 2027 |
Payments on account
If your last tax bill was £1,000 or more, HMRC usually asks you to pay towards next year’s bill in advance. These are payments on account: two payments, each half of last year’s bill, due on 31 January and 31 July. They include Class 4 National Insurance.
You don’t have to make them if more than 80% of last year’s tax was already paid another way, such as through a PAYE tax code.
If you end up owing more than you paid on account, the rest is a balancing payment, due by 31 January after the tax year ends.
Why your first big bill can be a shock
The first January you owe £1,000 or more, you pay last year’s full bill and the first payment on account for this year, at the same time. Say your 2025 to 2026 bill is £3,000 and you made no payments on account:
- By 31 January 2027: £3,000 for last year plus £1,500 on account, so £4,500.
- By 31 July 2027: the second £1,500 on account.
That’s £6,000 in six months on a £3,000 bill. Putting money aside as you earn is what stops it hurting. See how much tax to put aside.
If you expect a lower bill this year, you can ask HMRC to reduce your payments on account in your online account. If you reduce them too far, you’re charged interest on the difference.
If you’re late
For the 2025 to 2026 return:
- Filing late: £100 straight away.
- After 3 months: £10 a day, up to £900.
- After 6 months and again after 12 months: 5% of the tax due or £300, whichever is more.
- Paying late: 5% of the unpaid tax at 30 days, 6 months and 12 months, plus interest.
If you’ve joined Making Tax Digital, a points-based system replaces these penalties from the tax year you joined. For anyone who joined in April 2026, the 2025 to 2026 return still uses the penalties above.
How Kev helps
Kev’s tax summary adds up the invoices you’ve been paid, your expenses and your mileage as you go, and gives a rough idea of the tax on your profit so far, so January isn’t a guess.
Sources
This is general guidance, not tax advice. Rules can change, so check gov.uk or ask an accountant about your own situation.
Have your figures ready before January
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