Facts checked on GOV.UK on . Tax rules change, so check the dates before you act on them.
The dates
- 5 October 2026
- Tell HMRC you need to complete a return for 2025 to 2026, if you have not filed before or did not need to for 2024 to 2025. This date has passed.
- 31 October 2026
- Paper return must reach HMRC. This date has passed.
- 30 December 2026
- File online by 11:59pm if you want to pay through your tax code.
- 31 January 2027
- File online by 11:59pm. Pay the tax you owe by 11:59pm. First payment on account is also due, if you make them.
- 31 July 2027
- Second payment on account, if you make them.
If you register after 5 October 2026, HMRC will send a letter or email with a different filing deadline, three months from the date on it. The tax is still due on 31 January 2027.
Who has to file
- Sole traders who earned more than £1,000 before expenses
- Partners in a business partnership
- People who had to pay Capital Gains Tax
- People who must pay the High Income Child Benefit Charge outside PAYE
- Anyone with untaxed income, such as rent, tips, savings interest or dividends, who needs to report it
Penalties for filing late
- Straight away
- A £100 penalty.
- After 3 months
- A further £10 a day, up to £900.
- After 6 months
- A further 5% of the tax due or £300, whichever is greater.
- After 12 months
- Another 5% or £300, whichever is greater.
Penalties for paying late
HMRC charges 5% of the unpaid tax at 30 days, 6 months and 12 months, plus interest on the amount owed. If you have a reasonable excuse you can appeal a penalty.
Payments on account
Payments on account are two instalments towards next year’s bill, each usually half of last year’s tax, due on 31 January and 31 July. You must make them unless last year’s tax was under £1,000 or you paid more than 80% of it outside Self Assessment, for example through your tax code. If you earn more than estimated you pay a balancing payment by the following 31 January; if you earn less you may be able to claim a refund.
What to do next
If you are not sure whether you need a return, or you are close to a date, request a call-back and JT Accountancy will confirm what is needed. They also say that if you are behind with accounts or tax, the sooner you get in touch the better.
Sources: GOV.UK: Self Assessment tax returns, deadlines, GOV.UK: penalties, GOV.UK: understand your Self Assessment bill. This guide is general information published by Hull Accountant, not advice for your situation.