Self-Assessment Deadline 31 January 2025: Everything You Need to Know
The online deadline to file your 2023-24 Self-Assessment tax return and pay any tax owed is 31 January 2025. With the deadline now weeks away, here is a focused guide for anyone who still needs to file — including what information you will need, how the payment works, and what happens if you miss the date.
Do you need to file?
HMRC requires a Self-Assessment return from anyone who:
- Was self-employed with gross income over £1,000
- Received income from renting out property
- Earned over £100,000 from employment
- Had investment income (dividends or savings interest) above their allowances
- Received the High Income Child Benefit Charge (where one partner earned over £50,000 in 2023-24 — note: threshold was raised to £60,000 from April 2024 onwards)
- Had untaxed income of any kind over £2,500
- Received income from abroad
If you received a notice to file from HMRC, you must complete a return even if you believe you have no tax to pay. Failing to file when required still incurs the £100 penalty.
What you will need
- Your Government Gateway user ID and password (or Verify login)
- Your P60(s) from all employers for 2023-24
- P11D or P11D(b) if you receive benefits in kind (company car, private medical)
- Self-employment income and expense records
- Rental income and allowable expenses
- Any statements of dividends received
- Bank interest statements (or estimates from your bank accounts)
- Gift Aid donations made in 2023-24
Payment on Account: the hidden extra bill
If your 2023-24 tax liability exceeds £1,000 (and less than 80% was collected through PAYE), you will also owe the first Payment on Account for 2024-25 — calculated as 50% of your 2023-24 liability. This is also due on 31 January 2025. If you expect your 2024-25 income to be materially lower, you can apply to reduce your Payments on Account through your HMRC online account.
Penalties for late filing
The penalty regime is immediate and escalating:
- 1 day late: £100 fixed penalty
- 3 months late: £10/day (up to 90 days)
- 6 months late: 5% of tax owed or £300 (whichever is greater)
- 12 months late: further 5% or £300
Interest on unpaid tax currently runs at Bank of England base rate plus 2.5%.
HMRC contact and the HMRC app
If you need help with your return, HMRC's Self-Assessment helpline is 0300 200 3310 (Monday to Friday, 8am to 6pm). Wait times are typically longer in January. The HMRC app and online personal tax account at gov.uk/personal-tax-account allow you to view your tax code, PAYE history, and any pending liabilities before you call.
Conclusion
Filing early avoids January stress and means you know exactly what you owe — or whether HMRC owes you a refund. If you have been self-employed or had property income during 2023-24, use our self-employed tax calculator to cross-check your estimated liability before you file.