Miss a deadline and HMRC charges a penalty, even if you owe nothing. Here are the dates that matter.
Tax years
- 2025/26: 6 April 2025 to 5 April 2026
- 2026/27: 6 April 2026 to 5 April 2027
Key dates for the 2025/26 tax year
- 5 October 2026: register for Self Assessment if this is your first year
- 31 October 2026: paper return deadline
- 31 January 2027: online return deadline and balancing payment due
- 31 July 2027: second payment on account due (if you have to make them)
Payments on account
If your tax bill is over £1,000, HMRC usually asks for advance payments towards next year's bill, each half of this year's bill. They are due on 31 January and 31 July. Plan for this in your first year, as the January bill can be bigger than expected.
Late penalties
An online return filed even one day after 31 January brings an automatic £100 penalty, with more charges after 3, 6 and 12 months. Interest is also charged on tax paid late.
Stay ahead
Add your income and expenses as you go and FareTaxMate keeps a live estimate of your bill, so 31 January is never a surprise.
General information only, not tax advice. Rules can change – check GOV.UK or an accountant for your situation.