What is the deadline to register for Self Assessment?

You must tell HMRC you need to file by 5 October following the tax year you started earning. For income earned in the 2025/26 tax year, that deadline is 5 October 2026.

Do I need to register for Self Assessment?

Usually yes if, in the last tax year, you earned more than £1,000 from self-employment, started letting out a property, or had other untaxed income such as dividends or capital gains. If nearly all your tax already comes out of a salary, you may not need to.

What happens if I register late?

Missing 5 October isn't an automatic fine. The failure-to-notify penalty is based on tax paid late — so if you register as soon as you can and pay everything you owe by 31 January, there's usually no penalty. Register promptly though, because your UTR takes time to arrive.

How long does it take to get a UTR?

Your Unique Taxpayer Reference is posted to you, usually within a couple of weeks — longer around busy periods. You need it, plus an activated online account, before you can file, which is why registering early matters.

Deadlines · 5 min read · 20 July 2026

Going self-employed? Register with HMRC by 5 October

Everyone knows the 31 January tax deadline. Far fewer know about the one that comes first: if you started earning on the side last tax year, you need to tell HMRC by 5 October. Here's who it applies to, and how to beat it without a scramble.

The date: if you had income to declare in the 2025/26 tax year (6 April 2025 to 5 April 2026), you must register for Self Assessment by 5 October 2026.

Do you need to register?

You generally need to register if, during the last tax year, you:

earned more than £1,000 from self-employment or a side hustle (the trading allowance);
started renting out a property and made more than £1,000 from it;
had other untaxed income — dividends, capital gains, foreign income, or a chunky bit of savings interest;
need to file for another reason (higher earner, child benefit charge, and so on).

If nearly all your tax already comes out of a salary through PAYE, you probably don't need to. Not sure which side of the line you're on? Take our free 30-second check — no sign-up needed.

What "registering" actually does

Registering isn't the same as filing. It simply tells HMRC you'll be sending a return, and it gets you a UTR (Unique Taxpayer Reference) — the 10-digit number you need before you can file anything. The return itself isn't due until 31 January. Think of 5 October as putting your hand up, and January as handing the work in. Here's the full how-to-register walkthrough.

Why you shouldn't leave it to the last minute

Your UTR doesn't arrive instantly. HMRC posts it to you, usually within a couple of weeks — and longer around busy periods. You then need to activate your online account before you can actually file. Register in early October and that clock starts fine; register in mid-January and you can find yourself locked out of your own tax return with the deadline days away. Registering early is the single easiest way to take the January panic off the table.

What if you miss 5 October?

First, don't panic — this is where a lot of scaremongering gets it wrong. Missing 5 October is not an automatic fine.

The "failure to notify" penalty HMRC can charge is based on tax paid late — technically, the tax still unpaid at 31 January because you told them late. So if you register as soon as you realise, and pay everything you owe by 31 January, there's usually no penalty at all. The penalty only really bites if you're late on both counts — you didn't tell HMRC and you didn't pay on time.

So the plain-English version: register the moment you can, and make sure your tax is paid by 31 January. Do those two things and a missed 5 October rarely costs you anything — but don't dawdle, because that UTR still has to arrive in the post.

How to register

You register online at GOV.UK. If you're newly self-employed you'll use the self-employed route; if you have other untaxed income but aren't self-employed, there's a separate form. Either way, HMRC posts out your UTR, you activate your online account, and you're set up to file. Prefer not to wrestle with any of it? We register you and handle the return.

We'll register you and file the lot

New to this? We get you set up with HMRC and file your return for you — from £25 a month.

Get started →

Common questions

What's the deadline to register? 5 October following the tax year you started earning — so 5 October 2026 for 2025/26 income.

Do I definitely need to register? Usually yes if you earned over £1,000 self-employed, started letting a property, or had other untaxed income. Our free check will tell you.

What if I'm late? Not an automatic fine — register promptly and pay by 31 January and there's usually no penalty.

Related guides

How to register with HMRC — the step-by-step
Do I actually need to file? — who has to
Self Assessment deadlines — every date that matters
Our Self Assessment service — we register and file for you

This guide is general information, not personal tax advice. Rules, thresholds and deadlines can change — always confirm the current position on GOV.UK or ask us to check your situation.

← Back to the blog