This content originally appeared on DEV Community and was authored by Landolio
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.
This content originally appeared on DEV Community and was authored by Landolio
Landolio | Sciencx (2026-03-14T10:32:27+00:00) The UK freelancer tax calendar every developer should bookmark (2026/27). Retrieved from https://www.scien.cx/2026/03/14/the-uk-freelancer-tax-calendar-every-developer-should-bookmark-2026-27/
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