Self Assessment Deadline 2026 to 2027: Paper, Online and Registration Dates

Most people only remember 31 January, and that's fine if you file online. The dates that catch people out are the earlier ones: 5 October to register, 31 October for paper, and 30 December if you want what you owe collected through your tax code.

Here's every date for this tax year in one place, and what to do if you've already missed one.

Every Self Assessment date for the 2025 to 2026 tax year

Date	Deadline
6 April 2026	Earliest date you can send your return
5 October 2026	Tell HMRC you need to file, if you're new or didn't file last year
31 October 2026	Paper tax returns must reach HMRC by 11:59pm
30 December 2026	Online returns, if you want what you owe collected through your PAYE tax code
31 January 2027	Online tax returns by 11:59pm, and the deadline for what you owe

The tax year itself started on 6 April 2025 and ended on 5 April 2026.

The paper deadline is 31 October

If you still file on paper, HMRC must receive your return by 11:59pm on 31 October 2026. Note the word receive: posting it on the day isn't enough. You can send a paper return any time from 6 April 2026, so if paper's your route, send it early with tracking.

Miss 31 October on paper and you can still file online until 31 January 2027, as long as you have online sign-in details. Setting those up takes time, so start now if you need them. On a phone, the HMRC app can help once you're signed in.

The online deadline is 31 January

Online returns must be submitted by 11:59pm on 31 January 2027. That same date is the deadline for what you owe for the year. Two details worth knowing:

• If you don't know your profit for the whole year, you still have to send a return. GOV.UK has a page on what to do in that case.
• If you're employed and want what you owe collected through your tax code instead, you must submit online by 30 December 2026. Miss that and you'll have to settle it another way.

Online or paper: which to use

	Online	Paper
Filing deadline	11:59pm, 31 January 2027	11:59pm, 31 October 2026
Earliest you can send	6 April 2026	6 April 2026
Tax code collection option	Yes, if filed by 30 December 2026	No
Needs HMRC sign-in details	Yes	No

For most people, online wins: you get three extra months and an instant confirmation that HMRC has your return. Paper only makes sense if you can't get online sign-in details set up, or you're one of the special cases below that has to use paper.

If the dates confuse you, when the UK tax year starts and ends sets them out.

If you're registering for the first time

You must tell HMRC by 5 October 2026 if you need to file for the 2025 to 2026 tax year and you either haven't sent a return before, or you registered before but didn't need to file for 2024 to 2025. Telling HMRC late can mean a penalty.

If you register after 5 October, HMRC sends you a letter or email with your own filing deadline, 3 months from the date on it. The 31 January 2027 deadline for what you owe stays the same. New to this? Our tax tips for the self-employed are a good place to start.

What to gather before you file

• Your UTR and your HMRC sign-in details.
• Records of your self-employed income and expenses for 6 April 2025 to 5 April 2026.
• Details of any other income for the year, such as property income or savings interest.
• Your P60 or final payslip if you were also employed.
• Notes on anything unusual, like a large one-off job, so you don't forget it in January.

Having this in one folder is what turns filing from a weekend job into an evening.

Special cases

Who	Deadline
Trustees of a registered pension scheme	Paper return by 31 January 2027, no online option
Non-resident companies	Paper return by 31 January 2027, no online option
Partnerships with a company partner and an accounting date between 1 February and 5 April	Online 12 months from the accounting date, paper 9 months

If you've missed a deadline

GOV.UK's advice is simple: send the return as soon as you can to avoid further penalties. A late return today beats a perfect one next month, so don't wait to get every figure exact before you file.

And have your number to hand: how to find your National Insurance number.

How to make 31 January painless

1. Sign in to HMRC online once in the autumn to check your details still work.
2. Have your UTR number to hand, since you'll need it everywhere.
3. Pull your income and expense records together in December, not January.
4. File early. You can submit any time from 6 April, and filing early doesn't move the date you owe anything.
5. Watch for fake HMRC texts and emails. HMRC won't text you a link asking for your sign-in details.

My advice: put 31 October and 31 January in your calendar now, with a reminder two weeks before each. Most penalties come from forgetting, not from not knowing the rules.

Frequently asked questions

What is the Self Assessment deadline for 2027?

Online returns for the 2025 to 2026 tax year are due by 11:59pm on 31 January 2027. What you owe is due on the same date.

When is the paper Self Assessment deadline?

HMRC must receive paper returns by 11:59pm on 31 October 2026. Posting on the day isn't enough.

When must I register for Self Assessment?

By 5 October 2026 if you need to file for the 2025 to 2026 tax year and you're new or didn't file the year before.

What is the 30 December Self Assessment deadline?

It's the online filing date if you want what you owe collected through your PAYE tax code instead of settling it separately.

What happens if I miss the Self Assessment deadline?

You'll get a late filing penalty. GOV.UK advises sending the return as soon as possible to avoid further penalties.