Self Assessment:
deadlines, payments on account and penalties

If you’re self-employed, let out property, are a partner in a business or have other income that isn’t taxed at source, you’ll usually file a Self Assessment tax return. The dates are the same every year, so once you know them you can plan around them.

The deadlines

The tax year runs from 6 April to 5 April. Your return for a tax year is due the following autumn or winter:

What	Deadline
Tell HMRC you need to file, if you’re new	5 October
Paper return	31 October
Online return	31 January
Pay the tax you owe	31 January
Second payment on account	31 July

So for the 2025/26 tax year, which ended on 5 April 2026, the online return and payment are due by 11:59pm on 31 January 2027.

If you’re employed or get a pension, and you owe less than £3,000, file online by 30 December and HMRC can collect it through your tax code.

Payments on account

Payments on account are advance payments towards next year’s bill, including Class 4 National Insurance if you’re self-employed. Each one is half of last year’s bill, and they’re due on 31 January and 31 July.

You don’t have to make them if:

• last year’s bill was under £1,000, or
• more than 80% of your tax was already taken at source, for example through your tax code

If the two payments don’t cover the full bill, you pay the rest, the balancing payment, by 31 January after the tax year ends. That’s why your first year can come as a shock: on 31 January you may pay the whole of last year’s bill plus the first payment on account for this year.

If you expect your income to drop, you can ask HMRC to reduce your payments on account, online or with form SA303. If you reduce them too far, you’ll pay interest on the difference.

Penalties for filing late

If your return is late, the penalties build up:

• 1 day late: £100
• 3 months late: £10 a day, up to £900
• 6 months late: a further 5% of the tax due or £300, whichever is more
• 12 months late: another 5% or £300, whichever is more

The £100 applies even if you have no tax to pay.

Penalties for paying late

If you pay late, HMRC charges interest from the day after the deadline. On top of that, you’ll get a penalty of 5% of the tax unpaid at 30 days, again at 6 months and again at 12 months.

If you use Making Tax Digital for Income Tax, a different system applies: points for late returns, and late payment penalties that start after 15 days. Our Making Tax Digital guide covers it.

If you can’t pay in full

Contact HMRC as soon as you know you can’t pay, before the deadline. They may agree a payment plan if they think you can keep to it. Interest still runs on whatever is unpaid.

What you need to do

• If this is your first return, register with HMRC by 5 October after the tax year ends.
• Gather your income, expenses and bank statements for the tax year.
• File online by 31 January, earlier if you want the bill collected through your tax code.
• Check whether payments on account apply to you and put 31 July in your diary.
• If your income has dropped, look at reducing your payments on account.
• If you can’t pay, contact HMRC before the deadline about a payment plan.

Key dates

• 5 October: register if you need to file for the tax year that ended in April.
• 31 October: paper returns.
• 30 December: online returns, if you owe less than £3,000 and want it collected through your tax code.
• 31 January: online return, balancing payment and first payment on account.
• 31 July: second payment on account.

For the exact dates coming up, see our tax calendar.