Self assessment deadline: Key dates for registering, filing and paying

Published Friday 23 January 2026

Table of contents

• What are Self Assessment deadlines?
• 5 October 2026: Self Assessment tax registration deadline
• 31 October 2026: Self Assessment deadline for paper tax return
• 30 December 2026: Deadline to let HMRC collect Self Assessment payments through Pay As You Earn (PAYE)
• 31 January 2027: Online tax return payment and filing deadline
• 31 July 2027: Second online Self Assessment payment deadline
• How to file Self Assessment tax returns
• Managing Self Assessment deadlines with digital tools
• FAQs on Self Assessment deadlines

Key takeaways

• Register for Self Assessment by 5 October if you have untaxed income or capital gains above £3,000 to receive your unique taxpayer reference and avoid automatic penalties.
• Submit your tax return by 31 October for paper filing or 31 January for online filing, as missing these deadlines triggers penalties even if you owe no tax.
• Pay your Self Assessment tax by 31 January for the previous tax year's balance and first payment on account, with the second payment on account due by 31 July.
• Prepare for Making Tax Digital requirements from April 2026 by switching to HMRC-recognised software now, as paper returns and HMRC's online system will no longer be available for self-employed individuals and landlords.

What are Self Assessment deadlines?

Self Assessment deadlines are fixed dates set by HMRC for completing tax-related tasks throughout the year. To avoid penalties, make sure you meet each deadline, even if you don’t have any tax to pay.

Key deadline categories:

• Registration: Tell HMRC you need to file (5 October)
• Filing: Submit your completed tax return (31 October for paper, 31 January for online)
• Payment: Pay any tax owed (31 January and 31 July)
• PAYE collection: Request tax collection through salary (30 December)

5 October 2026: Self Assessment tax registration deadline

Self Assessment registration is the process of telling HMRC you need to file a tax return by 5 October. This deadline applies if you have untaxed income or capital gains above the annual exempt amount.

You must register by this date to:

• Receive your notice to file: HMRC sends this after registration
• Avoid penalties: Late registration can result in fines
• Get your unique taxpayer reference (UTR): required for filing your return

Do this through the Self Assessment registration form on the HMRC site.

Registration timeline by tax year:

• 2024/25 tax year: Register by 5 October 2025
• 2025/26 tax year: Register by 5 October 2026

Who needs to register:

• Untaxed income: self-employment, rental income, or other work you do alongside your main job
• Capital gains: Above £3,000 annual exempt amount (2024/25 and 2025/26)

31 October 2026: Self Assessment deadline for paper tax return

Paper tax returns must be filed by 31 October, three months earlier than online returns. Missing this deadline triggers penalties even if you owe no tax.

Paper vs online filing:

• Paper deadline: 31 October 2026
• Online deadline: 31 January 2027 (three extra months)
• Penalty risk: Same for both methods if deadlines are missed

In the coming years, paying income tax is going digital. Self-employed people and landlords will need to submit their returns using HMRC-recognised software, under Making Tax Digital for Income Tax (MTD for IT) rules. Switch to cloud-based software now to make the move to digital tax reporting easier.

Read the guide on Making Tax Digital deadlines for more details on the Income Tax Self Assessment (ITSA) timeline.

30 December 2026: Deadline to let HMRC collect Self Assessment payments through Pay As You Earn (PAYE)

Pay As You Earn (PAYE) collection lets HMRC spread your Self Assessment tax across your salary over 12 months instead of in one payment. You must request this by 30 December.

Eligibility requirements:

• Tax owed: Less than £3,000 (must be paid in full through PAYE)
• Employment status: Already pay tax through PAYE (employee or pension recipient)
• Filing deadline: Paper return by 31 October OR online return by 30 December

You can find the full criteria on the HMRC payment deadlines page.

31 January 2027: Online tax return payment and filing deadline

31 January is the deadline for filing online Self Assessment returns and paying your tax bill for the previous tax year (ending 5 April).

What's due on 31 January 2027:

• Online tax return: For 2025/26 tax year
• Tax payment: Any balance owed for 2025/26
• First payment on account: Advance payment towards 2026/27 tax bill (if applicable)

You may find some details are already filled in on your Self Assessment tax return. HMRC pre-populates certain information throughout the year, such as state and occupational pension. But, you'll need to fill in the rest using your own records.

31 July 2027: Second online Self Assessment payment deadline

Payments on account are advance payments towards your next year's tax bill, split into two instalments. The second payment is due 31 July.

31 July 2027 payment:

• Second instalment: Towards 2026/27 tax year
• Combined with: January 2027 first payment
• Reduces: Your final 2026/27 tax bill when calculated

Check out the HMRC guidance on self employed tax payment dates for more help.

How to file Self Assessment tax returns

Current filing options include online submission through HMRC's website or paper returns by post. This changes from April 2026.

From April 2026:

• Digital records: Mandatory for self-employed and landlords
• HMRC-recognised software: Required for submissions
• No longer available: HMRC online system or paper returns
• Who's affected: Self-employed individuals and property landlords

If you already keep digital records in HMRC-recognised software, you’ll find it easier to meet the new tax rules. For the full details, read our guide on how Self Assessment Tax Returns are changing: MTD for IT.

Managing Self Assessment deadlines with digital tools

Digital accounting software helps you stay on top of Self Assessment deadlines through automated reminders and real-time financial tracking. This reduces the stress of last-minute preparation.

Key deadline management features:

• Automated reminders: help you keep on top of important filing and payment dates
• Real-time calculations: See your estimated tax liability throughout the year
• Document storage: Keep all receipts and records in one secure place
• Direct submission: File returns through HMRC-recognised software

Getting started with cloud-based accounting now prepares you for Making Tax Digital requirements from April 2026. Try Xero for free to see how digital tools can simplify your Self Assessment.

FAQs on Self Assessment deadlines

Here are answers to common questions about Self Assessment deadlines.

What happens if you miss the Self Assessment registration deadline?

If you register on time, you avoid automatic penalties, even when you don’t have any tax to pay. Act immediately to minimize costs, and be vigilant for scams, as HMRC has received reports of over 4,800 Self Assessment scams targeting taxpayers under pressure.

Immediate actions:

• Register now: Complete registration as soon as possible
• Contact HMRC: Explain your situation directly
• Expect penalties: Failure to notify penalties start from £100

Ongoing risks:

• Late filing: Additional penalties for missed return deadlines
• Late payment: Interest and surcharges on unpaid tax

You can learn more about failure to notify penalties on the HMRC site. Learn what happens if you don't pay self-employment tax in our guide.

How long does Self Assessment registration take?

Self Assessment registration typically takes 10 to 15 minutes online, and you’ll usually get your unique taxpayer reference (UTR) by post within 10 working days.

Registration steps:

1. Start online: Visit gov.uk's 'Register for Self Assessment' page
2. Complete assessment: Answer questions to confirm if you need to register
3. Create account: Sign up for Government Gateway account if needed
4. Receive UTR: Posted to you within 10 working days
5. Get filing notice: HMRC emails or posts when your return is due

Keeping accurate records throughout the tax year means you only need to check and confirm details at filing time, rather than rebuild them from scratch.

Time-saving benefits:

• Automated calculations: Software handles complex tax computations
• Real-time tracking: Monitor income and expenses as they happen
• Direct integration: Connect bank accounts and payment systems
• Compliance support: Built-in guidance for tax requirements

Can you get an extension on Self Assessment deadlines?

You may be able to appeal a penalty if you have a reasonable excuse for filing or paying late. This could include unexpected illness or a family bereavement. HMRC reviews these on a case-by-case basis, so it's not guaranteed. It's always best to file and pay on time if you can.

What if you have no tax to pay but miss the filing deadline?

You can still receive a penalty for filing your tax return late, even if you don't owe any tax. The penalty for late filing is separate from any penalties for late payment. Be sure to submit your return by the deadline to avoid this.

How can I avoid missing Self Assessment deadlines?

The best way to stay on top of deadlines is to get organised early. Use a calendar to mark all the key dates. Keeping your financial records up to date with accounting software also makes filing much quicker and less stressful, as all your information is ready to go.