Tax deadlines sneak up on you. Every year I see devs in UK freelancer communities panicking about deadlines they didn't know existed.
Here's every date that matters for the 2026/27 tax year, in one place.
Key dates
| Date | What happens |
|---|---|
| 6 April 2026 | New tax year starts. MTD for Income Tax begins (income >£50k) |
| 5 October 2026 | Deadline to register for self-assessment (new filers) |
| 31 October 2026 | Paper tax return deadline |
| 30 December 2026 | File online if you want tax collected via PAYE |
| 31 January 2027 | Online filing + payment deadline for 2025/26 |
| 31 July 2027 | Second payment on account due |
The ones that catch people out
Payment on account
If your tax bill is over £1,000 (and less than 80% was collected at source), HMRC demands advance payments towards next year's bill. This doubles your January payment.
First-timers get absolutely blindsided by this. You think you owe £3,000 and HMRC says £4,500.
Full explanation of payment on account →
MTD quarterly submissions (new from April 2026)
If you earn over £50,000, you now need to:
- Keep digital records using compatible software
- Submit quarterly updates to HMRC
- File an end-of-period statement
The quarterly deadlines are roughly: 7 Aug, 7 Nov, 7 Feb, 7 May.
The 5 October registration trap
If you started freelancing this tax year and don't register by 5 October, you're technically late. HMRC rarely enforces this aggressively, but it can delay your UTR and Government Gateway access — which then makes you late for the actual filing deadline.
What to do right now
- Set calendar reminders for 31 January and 31 July
- Open a separate savings account and transfer 25-30% of profit monthly
- Track expenses as you go — don't leave it until January
- Check your MTD status if you earn over £50k
Free tools
I built a few tools that might help:
- Self-employed tax calculator — income tax + NI + take-home
- Day rate calculator — work out your ideal rate from target salary
- MTD readiness checker — 2-minute quiz
- Penalty calculator — see what late filing actually costs
- Expense tracker — browser-based, no signup, exports to CSV
All free, no accounts needed.
Anything I've missed? Happy to answer questions about UK freelance tax in the comments.
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