The 2025/26 tax year runs from 6 April 2025 to 5 April 2026. If you need to complete a Self Assessment tax return for that year, here are the dates to put in your diary.
The key dates
- 5 October 2026 — the deadline to tell HMRC you need to file, if you are newly self employed or have new income to declare.
- 31 October 2026 — the deadline if you file a paper tax return.
- 31 January 2027 — the deadline to file your return online, and to pay any tax you owe for 2025/26.
- 31 January 2027 — also the date your first payment on account for the next year may be due.
- 31 July 2027 — the date any second payment on account is due.
Who needs to file?
Common reasons include being self employed, earning rental income, being a company director with untaxed income, or earning over certain thresholds. If you are not sure, just ask us and we will check for you.
What happens if you are late
HMRC charges penalties even if you owe no tax:
- An automatic £100 penalty as soon as you miss the online filing deadline.
- Daily penalties if your return is more than three months late.
- Further penalties and interest on top if tax is paid late.
The good news is that these are completely avoidable with a little planning.
How to stay ahead
- Gather your income and expense records early, rather than in January.
- Register in good time if it is your first return.
- Better still, hand it to us and we will prepare, check and file it well before the deadline.
Never miss a deadline again
We track every date for you and chase nothing at the last minute. Your return is filed early, you know what to pay and when, and your weekends in January stay yours.