One missed date, one automatic fine
HMRC doesn't send a reminder the week before. Miss the 31 January filing deadline and you get an automatic £100 penalty even if you owe nothing — and it climbs fast after that. The good news: there are really only a handful of dates a sole trader has to keep an eye on, and they don't move much year to year.
This is the full calendar, in plain English: when to register, when to file, when to pay, and the new Making Tax Digital quarters that start landing from April 2026. Get these into your phone once and you'll never be caught out. Below we walk through each one, what triggers it, and what happens if you miss it.
The tax year you're working to
The UK tax year runs 6 April to 5 April. So the 2025/26 tax year covers 6 April 2025 to 5 April 2026, and everything below hangs off that. When people say "this year's tax return", they mean the return for the tax year that has just ended.
5 October — register for Self Assessment
If you started working for yourself during a tax year, you must tell HMRC by 5 October after the end of that tax year. So if you went self-employed at any point in 2025/26, your deadline to register is 5 October 2026. Leave it later and you risk a "failure to notify" penalty. Registration is a one-off — you don't do it every year. See our registering as a sole trader guide for the step-by-step.
Rule of thumb: earned more than £1,000 from self-employment in a tax year? That's above the £1,000 trading allowance, so you need to register and file. Under £1,000 and the trading allowance may cover you.
31 January — file online and pay your bill
This is the big one. By midnight on 31 January you must both:
- File your online Self Assessment tax return for the tax year that ended the previous 5 April; and
- Pay the tax you owe for that year (your "balancing payment").
So the return for 2025/26 (which ended 5 April 2026) is due by 31 January 2027. Miss it and there's an automatic £100 penalty, then daily penalties after three months, plus interest on anything unpaid. Filing early doesn't mean paying early — you still have until 31 January to pay, so many people file in the autumn and set the money aside.
Payments on account — 31 January and 31 July
Once your tax bill goes over £1,000, HMRC asks you to pay next year's tax in advance, in two instalments called payments on account. Each one is 50% of last year's bill:
- 31 January — balancing payment for last year plus your first payment on account for the current year.
- 31 July — your second payment on account.
Worked example: your 2025/26 bill is £3,000. On 31 January 2027 you pay the £3,000 plus £1,500 (first payment on account) = £4,500. Then on 31 July 2027 you pay another £1,500. That first January can be a shock — budget for it.
If your income has dropped, you can ask HMRC to reduce your payments on account — but if you reduce them too far, they charge interest on the shortfall. Our payments on account guide covers this in full.
6 April — the new tax year begins
The clock resets. From this date you can file the return for the year that just ended, and it's the earliest point to get your figures in. Filing in April or May rather than the following January means no last-minute panic and you know your bill months in advance.
MTD for Income Tax — the new quarterly dates
Making Tax Digital for Income Tax changes how (and how often) some sole traders report. From 6 April 2026 it applies if your combined self-employment and property income is over £50,000. The threshold drops to £30,000 from April 2027 and £20,000 from April 2028.
If you're in scope you'll keep digital records and send HMRC a quarterly update through compatible software. The standard quarters end 5 July, 5 October, 5 January and 5 April, with each update due roughly a month later (check the current dates with your software). You then confirm the year with a final declaration. It's more frequent, but each update is lighter than a full return. See MTD for sole traders for what to do now.
VAT — the clock is rolling, not fixed
VAT doesn't run to a fixed annual date. You must register once your taxable turnover exceeds £90,000 in any rolling 12-month period — that's any 12 consecutive months, not just the tax year. Once you cross it you have 30 days to register. Keep an eye on your rolling total as you grow; going over unnoticed is a common and expensive mistake. More in our VAT threshold guide.
Your at-a-glance calendar
- 5 October — deadline to register for Self Assessment (after your first tax year)
- 31 January — file online return + pay balancing payment + first payment on account
- 31 July — second payment on account
- 6 April — new tax year starts; earliest to file
- Quarterly (MTD, if in scope) — digital updates through software
- Rolling 12 months — register for VAT within 30 days of passing £90,000
Not sure which of these apply to you? The dates are simple; whether payments on account, MTD or VAT bite depends on your numbers. If you'd rather someone just handle the calendar and the filing,
get started with us and we'll keep you ahead of every one.
