Self assessment deadline: register, file and pay tax

Published Wednesday 22 April 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
• What happens if you miss a Self Assessment deadline
• FAQs on Self Assessment deadlines

Key takeaways

• Register for Self Assessment with HMRC by 5 October if you have untaxed income or capital gains above £3,000, as missing this date triggers a failure-to-notify penalty that grows the longer you delay.
• File your tax return online by 31 January rather than on paper by 31 October to give yourself three extra months, and pay any tax owed by the same January deadline to avoid immediate interest charges.
• Request PAYE collection by 30 December if you owe less than £3,000 and already pay tax through your salary, as this spreads your bill across 12 months instead of requiring a single lump sum payment.
• Switch to HMRC-recognised software now if you are self-employed or a landlord, as from April 2026 digital record-keeping and software submissions become mandatory, replacing paper returns and HMRC's online portal.

What are Self Assessment deadlines?

Self Assessment deadlines are the fixed dates HMRC sets for registering, filing your tax return, and paying any tax you owe. Missing these dates triggers a late filing penalty, even if you have no tax to pay.

Key deadline categories:

• register: tell HMRC you need to file by 5 October
• file: submit your completed tax return by 31 October (paper) or 31 January (online)
• pay: settle any tax owed by 31 January and 31 July
• request PAYE collection: ask HMRC to collect through your salary by 30 December

5 October 2026: Self Assessment tax registration deadline

5 October is the deadline to register for Self Assessment with HMRC. You must register by this date if you have untaxed income or capital gains above the annual exempt amount of £3,000.

Registering by 5 October allows you to:

• receive your notice to file from HMRC
• avoid penalties for late registration
• obtain your unique taxpayer reference (UTR) for filing your return

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

The registration deadline depends on the tax year. Here's the timeline:

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

You need to register for Self Assessment if you have certain types of income. Here's 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

31 October is the deadline for paper Self Assessment tax returns. This is three months earlier than the online deadline, and missing it triggers penalties even if you owe no tax.

You can choose between paper and online filing, but the deadlines differ. Here's how they compare:

• paper returns: due 31 October 2026
• online returns: due 31 January 2027, giving you three extra months
• penalties: apply equally to both methods if deadlines are missed

From April 2026, self-employed people and landlords must submit returns using HMRC-recognised software under Making Tax Digital for Income Tax (MTD for IT) rules.

Switching to cloud-based software now makes 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)

30 December is the deadline to request PAYE collection for your Self Assessment tax. This option lets HMRC collect what you owe through your tax code and spread your tax bill across your salary over 12 months instead of requiring one lump sum payment.

To use PAYE collection, you must meet certain criteria. Here are the eligibility requirements:

• maximum tax owed: less than £3,000
• current tax status: already paying tax through PAYE as an employee or pension recipient
• filing requirement: paper return submitted 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 your online Self Assessment return and paying your tax bill. For the 2025/26 tax year (ending 5 April 2026), this means filing and paying by 31 January 2027.

Several obligations fall on this date. Here's what's due on 31 January 2027:

• submit your online tax return for the 2025/26 tax year
• pay any balance owed for 2025/26
• make your first payment on account towards your 2026/27 tax bill, if applicable

HMRC pre-populates some details on your tax return, such as state and occupational pension information. You'll need to complete the rest using your own records.

31 July 2027: Second online Self Assessment payment deadline

31 July is the deadline for your second payment on account. Payments on account are advance payments towards your next year's tax bill, split into two equal instalments where each is half of the tax you owed last year.

Your 31 July 2027 payment covers part of your advance tax obligations. Here's what it includes:

• covers the second instalment towards your 2026/27 tax year
• combines with your January 2027 payment to form your total advance payment
• reduces your final tax bill when HMRC calculates what you owe for 2026/27

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

How to file Self Assessment tax returns

Filing your Self Assessment tax return can currently be done online through HMRC's website or by posting a paper return. From April 2026, these options change for self-employed individuals and landlords if their total annual income is over £50,000.

From April 2026, new requirements apply to certain taxpayers. Here's what changes:

• keep digital records: mandatory for self-employed individuals and landlords
• use HMRC-recognised software: required for all submissions
• lose access to current systems: HMRC's online portal and paper returns will no longer be available
• check if you're affected: self-employed individuals and property landlords must comply

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.

What happens if you miss a Self Assessment deadline

Missing a deadline means you'll face penalties, even if you have no tax to pay. It's always best to file and pay on time to avoid these extra charges.

Late registration penalties

Notify HMRC promptly that you need to register for Self Assessment to avoid a failure-to-notify penalty. These charges can escalate the longer you delay.

Late filing penalties

File your tax return on time to avoid an immediate fixed penalty. If you continue to delay, the penalties increase.

• One day late: you receive an initial fixed penalty
• Three months late: daily penalties apply up to a maximum amount
• Six months late: HMRC charges a further penalty based on a percentage of the tax due
• Twelve months late: HMRC adds another penalty, which can be higher for deliberate errors

Late payment penalties and interest

Payment penalties are separate from filing penalties. HMRC charges interest on any unpaid tax from the payment deadline.

• Interest charges: HMRC applies interest to unpaid tax immediately after the deadline
• Thirty days late: HMRC charges an initial penalty on the unpaid tax
• Six months late: HMRC adds an additional penalty to the remaining balance
• Twelve months late: HMRC adds a final penalty to any tax still outstanding

If you have a reasonable excuse for missing a deadline, you may be able to appeal the penalty through HMRC.

FAQs on Self Assessment deadlines

Here are answers to common questions about Self Assessment deadlines.

What is the deadline for Self Assessment registration?

The deadline to register for Self Assessment is 5 October following the end of the tax year in which you had untaxed income or capital gains above the annual exempt amount.

Can I file my Self Assessment return after 31 January?

You can submit your return after 31 January, but you'll face automatic penalties. The initial penalty starts from one day late, with additional charges applying the longer you delay.

What happens if I can't pay my tax bill by the deadline?

Contact HMRC as soon as possible if you can't pay on time. They may arrange a payment plan, but interest will still apply to the outstanding balance from the original deadline.

Do I need to register for Self Assessment if I'm self-employed?

Yes, you must register for Self Assessment if you're self-employed and your income is above the trading allowance of £1,000 per year.

What is a payment on account?

A payment on account is an advance payment towards your next year's tax bill. You make two payments on account each year, in January and July, each representing half of your previous year's tax bill.