UK Self-Employed Tax Deadlines 2026/27: The Complete Calendar
By Ben, Founder of Solofold · Published May 2026 · 5 min read
I missed a tax deadline once in 20 years. The £100 automatic penalty arrived before I even realised I was late. This guide exists so you never have that experience.
The essential dates — every UK sole trader needs these
5 April 2026
End of 2025/26 tax year
The tax year closes. Start organising your 2025/26 records now. You have until 31 January 2027 to file and pay.
6 April 2026
Start of 2026/27 tax year
New tax year begins. Start tracking income and expenses from this date. All records from 6 April 2026 belong to the 2026/27 tax year.
31 July 2026
Second Payment on Account due
If your 2024/25 tax bill exceeded £1,000, your second Payment on Account is due today. This is 50% of last year's tax bill. Missing this triggers interest immediately. See our Payments on Account guide.
5 October 2026
Self-employment registration deadline
If you started self-employment in the 2025/26 tax year and have not yet registered with HMRC, today is your deadline. Late registration penalties apply from tomorrow.
31 October 2026
Paper Self Assessment deadline (if applicable)
If you file a paper tax return (not applicable to most — MTD requires digital from April 2026), it must reach HMRC today. Most sole traders file online and use the January deadline instead.
31 January 2027
THE BIG ONE — Online Self Assessment + payment due
Three things are due on this date:
1. Your 2025/26 Self Assessment tax return filed online
2. Any remaining 2025/26 tax balance paid
3. First Payment on Account for 2026/27 (if applicable)
Missing this costs you an immediate £100 penalty — even if you owe no tax.
31 July 2027
Second Payment on Account for 2026/27
Already planning ahead: mark this date now. Set money aside each month from April 2026 so July 2027 is never a surprise.
What happens if you miss a deadline
1 day late filing: Automatic £100 penalty. No exceptions. No appeals for simply being late.
3 months late: Additional £10/day penalty, up to 90 days (£900 maximum on top of the £100).
6 months late: Further penalty of 5% of tax owed (or £300, whichever is higher).
12 months late: Another 5% of tax owed (or £300, whichever is higher).
Late payment interest: HMRC charges interest on unpaid tax from the deadline date. Currently 7.5% per annum. Starts immediately on the day after the deadline.
VAT deadlines (if VAT registered)
If your turnover exceeds £90,000 you must register for VAT. VAT returns are typically filed quarterly — one month and seven days after each quarter end.
Standard quarterly deadlines:
Quarter ending 31 March → VAT due 7 May
Quarter ending 30 June → VAT due 7 August
Quarter ending 30 September → VAT due 7 November
Quarter ending 31 December → VAT due 7 February
How to never miss a deadline
Set calendar reminders now. Add every deadline above to your phone calendar with a 2-week advance warning. Do it today — not later.
File early, not late. January 31 is the deadline, not the target. Aim to file by December. You get the same result and zero January stress.
Keep records current. If you update your records weekly, January is just a data entry exercise. If you do it annually, January is a disaster recovery operation.
Know your Payment on Account amount now. Don't wait until January to discover you owe an extra 50% on top of your tax bill. Use the free tax estimator to see your likely bill before the deadline.
Know your tax bill before January
The Tax Year Companion calculates your estimated tax as you go. By December, you know exactly what you owe — no surprises, no panic, no penalty.
Get the Tax Year Companion (£69)Try the free tax estimator first →