What is the Self Assessment deadline for 2026?

For the 2025/26 tax year, the online return and any tax owed are due by 11:59pm on 31 January 2027. A paper return must reach HMRC by 31 October 2026, and you must tell HMRC you need to file by 5 October 2026 if you are new to Self Assessment.

Is the payment deadline the same as the filing deadline?

For online returns, yes: both are 31 January. If you file a paper return you get an earlier filing date of 31 October, but the tax is still due by 31 January.

What if I only registered after 5 October?

HMRC sets a different filing deadline, three months from the date of its letter or email. The payment deadline remains 31 January 2027.

When are the second payments on account due?

31 July. The first payment on account is due with your balancing payment on 31 January. Each is normally half of the previous year's tax bill.

Can I pay my bill through my tax code?

In some cases, if you file online by the tax code cut-off. GOV.UK gives 30 December 2026 for the 2025/26 return. It only applies to small bills that meet HMRC's conditions, so check before relying on it.

What happens if I miss the deadline?

HMRC charges an automatic £100 penalty for a late return, with further penalties building over 12 months, and separate penalties and interest for late payment.

Self Assessment Deadlines 2026

Self Assessment tax return guidance for UK taxpayers, in navy and gold

The key dates

These dates come from GOV.UK for the tax year 6 April 2025 to 5 April 2026:

5 October 2026: the deadline to tell HMRC you need to complete a tax return, if you have not filed before.
31 October 2026: HMRC must receive a paper return by 11:59pm.
30 December 2026: the last day to file online if you want to pay your bill through your tax code (only available where HMRC's conditions are met).
31 January 2027: file your online return and pay the tax you owe, both by 11:59pm.
31 July: second payment on account, if you make them.

Registering late

If you register after 5 October 2026, HMRC gives you a different filing deadline, which GOV.UK says is three months from the date on the letter or email. The deadline to pay stays at 31 January 2027, so do not assume a later filing date delays your payment.

How to register for Self Assessment

Payments on account

If you make payments on account, they are due on 31 January and 31 July. Each is normally half of your previous year's bill. The first one falls on the same day as your balancing payment, which is why the January bill can be large.

Payments on account explained

Do not leave it to the last day

The penalties for missing 31 January start immediately, so file early where you can. Filing early does not bring the payment date forward, but it tells you what you owe with time to plan for it.

What the penalties are

A note on future years

These dates apply to the 2025/26 return. The Making Tax Digital rules for Income Tax began on 6 April 2026 for sole traders and landlords with qualifying income above £50,000, and change how those taxpayers report income for 2026/27 onwards. They do not change the 31 January 2027 deadline for the 2025/26 return.

MTD for Income Tax explained

Need a hand with your return?

We prepare and file Self Assessment returns for directors, sole traders and landlords, and tell you exactly what is due and when before anything is submitted. Call 0114 327 1480.

Our Self Assessment service

Self Assessment deadlines for the 2025/26 tax year