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Self AssessmentUpdated 2026-10-19

When is my Self Assessment tax return due?

Quick Answer

The deadline for online Self Assessment is 31 January following the end of the tax year. For 2025/26 (ending 5 April 2026), the deadline is 31 January 2027. For 2026/27 (ending 5 April 2027), it is 31 January 2028.

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Detailed Explanation

Self Assessment deadlines for 2025/26 tax year

  • Tax year ends: 5 April 2026
  • Register for Self Assessment: 5 October 2026 (if first time)
  • Paper return deadline: 31 October 2026
  • Online return deadline: 31 January 2027
  • Payment deadline: 31 January 2027

Payment on Account dates

- First payment on account: 31 January 2027 (for 2026/27 tax year) - Second payment on account: 31 July 2027 (for 2026/27 tax year) - Balancing payment: 31 January 2027 (for 2025/26 tax year)

The 2026/27 tax year (ending 5 April 2027) follows the same pattern one year later, with the online return and payment due by 31 January 2028.

Who must file Self Assessment? - Self-employed with income over £1,000 - Company directors (usually) - Partners in partnerships - Landlords with rental income - High earners (£150,000+) - Those with complex tax affairs - Those with untaxed income

Late filing penalties

- 1 day late: £100 - 3 months late: £10/day up to 90 days (£900 max) - 6 months late: Greater of £300 or 5% of tax due - 12 months late: Greater of £300 or 5% of tax due (can be more in serious cases)

Late payment interest

Currently around 7.75% (Bank of England base rate plus 4%)

Source: HMRC Self Assessment Deadlines

Real-World Examples

Late Submission Penalty

John, a freelance graphic designer, forgets to file his Self Assessment return by the 31st January deadline. HMRC automatically issues a £100 late filing penalty, which increases the longer the return remains outstanding.

Payment on Account and Cash Flow

Sarah runs a small e-commerce business. She knows her first payment on account for the 2026/27 tax year is due on 31st January 2027, so she proactively sets aside funds each month from her profits to ensure she has sufficient cash available to meet the payment deadline without impacting her business's day-to-day operations.

Switching to Online Filing

Mark used to submit his Self Assessment via paper returns. He switches to online filing to take advantage of the later deadline (31st January), giving him more time to gather his records and complete his return accurately. He uses accounting software integrated with HMRC for seamless submission.

Common Mistakes to Avoid

  • Failing to register for Self Assessment by the 5th of October if you are newly self-employed or a new company director required to file.
  • Assuming you don't need to file if your income is below the personal allowance; other factors like dividends or untaxed income can trigger a filing requirement.
  • Missing the 31st January deadline because you underestimate the time needed to gather all the required information, such as bank statements and expense receipts.
  • Forgetting that even if you pay your tax bill on time, a late filing penalty still applies if you submit your return even one day late.

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

Contact HMRC as soon as possible to discuss a payment plan. They may offer a 'Time to Pay' arrangement, but interest will accrue on the outstanding balance from the due date.

Can I get an extension on the Self Assessment deadline?

Extensions are only granted in very exceptional circumstances, such as a serious illness or a major disruptive event. You must apply to HMRC in advance, providing evidence to support your request.

How do I pay my Self Assessment tax bill?

You can pay online via the HMRC website using your debit or credit card, through your online bank account, or by setting up a direct debit. Payments can also be made at your bank or building society but allow time for the payment to reach HMRC.

What records do I need to keep for my Self Assessment?

You must keep records of all income and expenses related to your self-employment or director duties for at least five years after the 31st January submission deadline. This includes invoices, receipts, bank statements, and mileage logs.

Practical Tips

  • Set up email reminders well in advance of the deadlines (both for filing and payment) to avoid missing them.
  • Use accounting software or a spreadsheet to track your income and expenses throughout the year, making the Self Assessment process much easier.
  • If you're unsure about any aspect of your Self Assessment, seek professional advice from an accountant or tax advisor.
  • Check your HMRC online account regularly to ensure your contact details are up to date and to review any communications from HMRC.

Related Questions

Do company directors need to file Self Assessment?

Usually yes. Most directors need to file Self Assessment if they receive dividends, salary above £100,000, or have other income. HMRC typically writes to new directors to register.

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