Self Assessment Deadlines — 2025/26
Updated for the 2025/26 tax year
If you are self-employed, a landlord, a company director, or earn income that is not taxed at source, you must file a Self Assessment tax return. Missing deadlines means automatic penalties — here are all the dates you need.
Key Dates for 2025/26 Tax Year
| Date | What |
|---|---|
| 6 April 2025 | 2025/26 tax year begins |
| 5 October 2025 | Deadline to register for Self Assessment (if new) |
| 31 October 2026 | Paper tax return deadline |
| 31 January 2027 | Online tax return deadline + pay tax owed + 1st payment on account |
| 31 July 2027 | 2nd payment on account |
| 5 April 2026 | 2025/26 tax year ends |
Payments on Account
If your tax bill is over £1,000(and less than 80% was collected at source), HMRC requires advance payments toward next year’s bill:
- 31 January:50% of the previous year’s tax bill
- 31 July: Another 50%
- Any difference is settled with the “balancing payment” the following 31 January
Late Filing Penalties
| How Late | Penalty |
|---|---|
| 1 day late | £100 (even if no tax owed) |
| 3 months late | £10/day for up to 90 days (max £900) |
| 6 months late | £300 or 5% of tax due (whichever is higher) |
| 12 months late | Another £300 or 5% of tax due — can be up to 100% in serious cases |
Late payment interest is charged at Bank of England base rate + 2.5% on any unpaid tax from the due date.
Who Needs to File?
- Self-employed with income over £1,000
- Partners in a business partnership
- Company directors (unless only PAYE income)
- Landlords with rental income
- Income over £150,000 (must file even if all PAYE)
- Capital gains above the exempt amount (£3,000)
- High Income Child Benefit Charge (income over £60,000)
- Foreign income that needs declaring
- Untaxed income over £2,500 (e.g. tips, commission)
Practical Tips
- File early — you can submit from 6 April but payment is not due until 31 January. Filing early gives you months to budget.
- Set up a Budget Payment Plan with HMRC to spread payments monthly via direct debit.
- If you cannot pay on time, contact HMRC before the deadline to arrange a Time to Pay plan — this can prevent penalties.
- Keep all receipts and records for 5 years after the 31 January submission deadline.