Tax Tips & HMRC Deadlines
Self-Assessment Deadlines You Can't Afford to Miss
If you're a sole trader, landlord or company director filing your own Self-Assessment, the calendar matters as much as the numbers. Missing a date doesn't just cost money — it adds stress you don't need.
The key dates
- 5 October — deadline to register for Self-Assessment if you're newly self-employed
- 31 October — paper tax return deadline
- 31 January — online tax return deadline AND balance of tax due
- 31 July — second payment on account due (if applicable)
What happens if you're late
HMRC applies an automatic £100 penalty the day after the deadline, even if you owe no tax. After three months, daily penalties of £10 kick in, capped at £900, with further penalties at 6 and 12 months on top of interest on any unpaid tax.
How to stay ahead of it
The businesses that never scramble in January are the ones who keep their bookkeeping current all year round. If your records are up to date by November, filing becomes a formality rather than a fire drill.
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