Do I need to file a Self Assessment tax return?

Who needs to file a Self Assessment return?

HMRC requires a Self Assessment return if any of the following applied in the last tax year:

• You were self-employed as a sole trader and earned more than £1,000
• You were a partner in a business partnership
• You were a company director (unless non-profit with no pay)
• Your total taxable income exceeded £100,000
• You had untaxed income over £2,500 from rent, savings interest, dividends, or other sources
• You or your partner received Child Benefit and one of you earned over £60,000
• You have foreign income or lived abroad for part of the year
• You have capital gains to report

Key deadlines for 2025/26

The 2025/26 tax year ran from 6 April 2025 to 5 April 2026.

• 31 October 2026 — paper returns due
• 31 January 2027 — online returns due and any tax owed must be paid
• 31 July 2027 — second payment on account (if applicable)

Over 740,000 people filed their 2025/26 return in April 2026 — the first month of the tax year. Filing early means knowing your bill sooner and the option to spread costs via HMRC's budget payment plan.

The new penalty regime

HMRC's points-based late-filing penalty system is now fully in force. Each late submission earns 1 penalty point. Reaching the threshold (2 points for annual filers) triggers a £200 fixed penalty. Further daily penalties of £10 apply from 3 months late, and 5% of tax owed at 6 and 12 months.

How to register for Self Assessment

1. Go to gov.uk/self-assessment and sign in with your Government Gateway account
2. If you don't have one, create a Government Gateway account — you'll need your National Insurance number
3. Select your reason for registering (self-employment, landlord, director, etc.)
4. HMRC will post your Unique Taxpayer Reference (UTR) within 10 working days

Register by 5 October 2026 if you need to file a 2025/26 return for the first time.

Reliefs you might be missing

• Working from home costs (flat rate or actual expenses)
• Mileage at HMRC's approved rate (45p/mile for first 10,000 miles)
• Professional subscriptions and memberships
• Equipment and tools purchased for work
• Pension contributions
• Charitable donations under Gift Aid

See our full guide to tax reliefs for a complete list with worked examples.