Self Assessment deadlines

The dates to know for the 2025/26 tax year, who needs to file and what happens if you are late.

The key dates for 2025/26

The 2025/26 tax year ended on 5 April 2026. The dates for that year's return are below.

Dates

  • 5 October 2026: register for Self Assessment if you have not filed before.
  • 31 October 2026: deadline for a paper tax return.
  • 30 December 2026: file online by this date if you want HMRC to collect a small bill through your tax code.
  • 31 January 2027: deadline to file online and to pay what you owe.
  • 31 July 2027: second payment on account, if you pay in instalments.

Who needs to file

Use the GOV.UK checker if you are unsure.

Payments on account

If your bill is more than £1,000 and less than 80% of your tax is collected at source, HMRC asks you to pay in advance. You pay two instalments, each half of last year's bill, on 31 January and 31 July. Any difference is settled with the next 31 January payment.

What happens if you are late

A late filing penalty starts at £100, even if you owe no tax, and further penalties and interest build up the longer it goes on. If you cannot pay in full, contact HMRC early about a payment plan.

Where to learn more

This guide is for information only and is not tax or financial advice.

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