Self Assessment deadlines 2026 and 2027

The UK tax year runs from 6 April to 5 April. Your return and most of your tax are due the following January, with payments on account in between. These are the dates that matter for sole traders and landlords.

Updated 28 September 2026 · England, Wales, Scotland and Northern Ireland

Key dates

Date	What's due
5 October 2026	Register for Self Assessment if you started working for yourself (or had new untaxed income) in 2025/26
31 October 2026	Paper return for 2025/26
30 December 2026	Online return for 2025/26 if you want tax under £3,000 collected through your PAYE code
31 January 2027	Online return for 2025/26, the balance of 2025/26 tax, 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 started in 2026/27
31 January 2028	Online return and balance for 2026/27, first payment on account for 2027/28

Payments on account

If your last Self Assessment bill was £1,000 or more, HMRC asks you to pay next year's tax in advance: two payments, each half of last year's bill, due 31 January and 31 July. Then on the following 31 January you pay any balance, or get a refund if you paid too much.

This is why the first January after a good first year hurts: you pay the whole of year one plus half of year one again as the first payment on account for year two. You don't make payments on account if at least 80% of your tax was already collected at source, for example through PAYE.

If you know this year's profit will be lower, you can ask HMRC to reduce your payments on account, online or on form SA303. Reduce them too far and you'll pay interest on the shortfall.

Penalties for filing late

1 day late: £100, even if you owe nothing.
3 months late: £10 a day for up to 90 days (up to £900).
6 months late: another £300 or 5% of the tax due, whichever is higher.
12 months late: another £300 or 5%, or more in serious cases.

Paying late

Interest runs from the due date at the Bank of England base rate plus 4%. Tax still unpaid 30 days after the deadline also gets a 5% penalty, with further 5% penalties at 6 and 12 months. If you can't pay in full, you can often set up a Time to Pay plan online, which stops the extra penalties.

If you're in Making Tax Digital for Income Tax from April 2026, a newer points-based penalty system applies to your returns and updates instead.

How much to set aside

The UK Self Assessment calculator shows income tax and Class 4 National Insurance on your 2026/27 profit, what to put away each month and your likely payments on account.