If you started working for yourself during the last tax year — perhaps you went freelance, picked up a side hustle that grew, or set up as a sole trader — there's an important date on the horizon that's easy to miss. You have until 5 October 2026 to tell HMRC you need to complete a Self Assessment tax return for the 2025/26 tax year. Register late and you could face a penalty, so it pays to sort it sooner rather than later.
Here's what registering involves, who actually needs to do it, and the deadlines that follow.
Do you need to register?
The 2025/26 tax year ran from 6 April 2025 to 5 April 2026. You'll generally need to register for Self Assessment if, during that period, any of the following applied:
- You were self-employed as a sole trader and earned more than £1,000 (before deducting expenses) from that work.
- You became a partner in a business partnership.
- You had other untaxed income — for example from renting out property, tips, commission, dividends, savings or investments — that HMRC couldn't collect through your tax code.
- You (or your partner) received Child Benefit and had income high enough to trigger the High Income Child Benefit Charge.
The £1,000 trading allowance is the key figure for the newly self-employed. If your total self-employed income for the year was £1,000 or less, you usually don't need to register or report it at all. Earn more than that and you're into Self Assessment territory — even if, after expenses, you made little or no profit.
If you're not sure whether a hobby has tipped over into a taxable trade, it's a common grey area, and one we're always happy to talk through.
The deadline that matters now: 5 October 2026
The registration deadline is 5 October following the end of the tax year in which you first had income to report. So for income earned in 2025/26, you must register by 5 October 2026.
Miss it and HMRC can charge a "failure to notify" penalty. The reassuring part is that if you register on time, then file your return and pay any tax due by the later deadlines, there's usually nothing to pay by way of penalty — the charge is tied to tax that goes unpaid as a result of registering late.
Registering isn't instant, either. HMRC sends you a Unique Taxpayer Reference (UTR) by post, and you'll then set up your online account and receive an activation code — a process that can take a couple of weeks. Leaving it until the last minute risks missing the later filing deadline simply because your login wasn't ready in time.
What happens after you've registered
Once you're in the system, these are the dates to keep in view for your 2025/26 return:
- 5 October 2026 — deadline to register for Self Assessment.
- 31 October 2026 — deadline if you file a paper tax return.
- 31 January 2027 — deadline to file online, and to pay any tax you owe for 2025/26.
- 31 January 2027 — your first payment on account may also fall due, if your bill is large enough, with a second on 31 July 2027.
Most people now file online, which gives you the full window through to 31 January. If this is your first return, remember that the January payment can cover both the tax for the year just gone and a payment on account towards the next — so the bill is sometimes larger than first-timers expect. Setting money aside as you earn is the simplest way to avoid a nasty surprise.
A quick word on record-keeping
From your first day of trading, keep a record of your income and your business expenses — invoices, receipts, bank statements and mileage all count. Good records make your return far quicker to complete and help you claim every allowable expense you're entitled to, which brings your tax bill down. Keep them for at least five years after the 31 January filing deadline, as HMRC can ask to see them.
It's also worth being aware of what's coming next. Making Tax Digital for Income Tax is phasing in from April 2026 for those with higher self-employment and property income, bringing quarterly digital updates in place of a single annual scramble. Getting into good habits with digital records now will make that transition far smoother.
We can take it off your plate
Registering, filing and paying on time is perfectly manageable — but it's also one of those jobs that's easy to put off until it becomes stressful. If you'd rather not wrestle with UTRs, activation codes and deadlines, we handle the whole process for sole traders, freelancers and partnerships every day — from getting you registered correctly to preparing and submitting your return and telling you exactly what to pay and when.
If you became self-employed in the last year, now is the ideal time to get set up so the 5 October deadline looks after itself. Get an instant quote or book a call and we'll make sure you're registered properly and comfortably ahead of every deadline.
This article is general guidance, not personal tax advice. Your circumstances may differ, so please get in touch for advice tailored to you.