What happens if I miss the 31 January tax return deadline?
I'm worried I've left it too late to file my Self-Assessment return for last tax year.
Asked by Anonymous on 9 June 2026
1 Answer
You'll get an automatic £100 penalty from HMRC even if you have no tax to pay, as long as the return is filed within 3 months of the deadline. After that, daily penalties of £10 build up (capped at 90 days), with further penalties at 6 and 12 months on top. If you have a reasonable excuse (illness, bereavement, etc.) you can appeal, but it's best to file as soon as possible to stop the clock and speak to an accountant if the bill is mounting up.