When do I need to register as self-employed in the UK?

By 5 October following the end of the tax year in which your gross self-employed income first went over £1,000. The tax year runs 6 April to 5 April, so income earned in the 2026/27 year must be registered by 5 October 2027, with the first return due by 31 January 2028.

Do I need to register as self-employed for a side hustle?

Only if your gross self-employed income across everything you do is more than £1,000 in a tax year, or you need to file a return for another reason. Below that the trading allowance covers you and you do not have to tell HMRC.

How long does it take to get a UTR number?

HMRC posts your ten-digit Unique Taxpayer Reference after you register, and it typically takes a couple of weeks, longer close to the January deadline. An activation code for the online service usually arrives separately, so register well before you need to file.

What happens if I register late?

HMRC can charge a failure-to-notify penalty calculated on the tax you should have paid, and filing late brings a separate automatic penalty that escalates over time. If you are already late, register now rather than waiting, an unprompted disclosure is treated far more leniently than one HMRC has to chase.

How to register as self-employed in the UK: the deadlines and the steps

Registering is a fifteen-minute form. The part that costs people money is the timing, because the deadline is not the one most people assume.

Do you need to register at all?

You must register for Self Assessment if your gross self-employed income for a tax year is more than £1,000. Gross means the total your customers paid, before platform fees, fuel or materials.

You are also required to register if you need to file for another reason, untaxed income, high-income child benefit charge, capital gains, and so on, but for most taskers the £1,000 test is the whole question. See the trading allowance explained for what counts.

Under £1,000 and you do nothing. Over it, keep reading.

The deadline nobody expects: 5 October

The tax year runs 6 April to 5 April. You must tell HMRC by 5 October following the end of the tax year in which you passed £1,000.

So if you went over £1,000 in, say, November 2026, that is the 2026/27 tax year, which ends 5 April 2027, your registration deadline is 5 October 2027, and your first return is due by 31 January 2028.

That is a long runway, and it is exactly why people miss it. Register as soon as you know you are over. There is no downside to being early and a failure-to-notify penalty for being late, calculated on the tax you should have paid.

What you need to hand

Your National Insurance number
Your address and date of birth
The date you started trading (the date you first earned, not the date you registered)
What kind of work you do, in plain words

You register on gov.uk. Sole trader is the default and the right answer for almost everyone starting out, no Companies House filings, no separate accounts, no corporation tax return.

What arrives, and in what order

A Government Gateway account, created during registration. Write the user ID down somewhere that is not a browser you might wipe.
Your UTR, a ten-digit Unique Taxpayer Reference, posted to you. Allow a couple of weeks, longer near the January deadline. You cannot file without it.
An activation code for the online service, also by post, usually separately. It expires, so use it when it arrives.

Every one of these steps is postal, which is why "I'll register in January" ends badly.

Then: 31 January

Date	What
5 October after the tax year ends	Register with HMRC
31 October	Deadline if you file on paper
31 January	Deadline to file online and to pay the tax
31 July	Second payment on account, if you have one

Filing late triggers an automatic penalty even when you owe nothing, and it escalates the longer it runs. File on time even if you cannot pay, the penalties for the two things are separate, and HMRC will discuss a payment plan.

Payments on account catch out almost every first-timer. If your bill is above a set amount and most of your tax is not collected at source through PAYE, HMRC asks for half of it again on 31 January and half again on 31 July, as an advance on next year. Your first January bill can therefore be one and a half times what you calculated. Check the current threshold on gov.uk, and put money aside for it.

A sane rule while you are learning: move 25-30% of every payment into a separate savings account the day it lands, and do not touch it.

National Insurance

Two classes apply to self-employment, and both are worked out automatically from the profit figure in your return.

Class 4 is a percentage of profits above a lower limit, with a reduced rate above an upper limit. Rates and both limits are set each year at the Budget.
Class 2 has changed significantly in recent years. It is no longer a flat weekly charge for most self-employed people, and those with profits above the relevant threshold get a qualifying year for the state pension without paying it. If your profits are low, you may want to pay Class 2 voluntarily to protect your state pension record, it is one of the cheapest ways to buy a qualifying year.

Because the rates and thresholds move every April, look them up on gov.uk when you file rather than trusting a figure from a guide, this one included.

What changes at £90,000

VAT. If your taxable turnover passes £90,000 in any rolling 12-month period, you must register for VAT within 30 days of the end of the month in which you crossed it. This is a rolling test, not a tax-year one, so a strong autumn can trip it.

The consequences are real: you add VAT to what you charge, which makes you roughly 20% more expensive to domestic customers who cannot reclaim it, and you file VAT returns. You also reclaim VAT on what you buy, which matters if you are buying materials.

Most taskers never approach this. If you can see it coming, that is the moment to talk to an accountant about whether a limited company, the flat-rate scheme, or restructuring makes sense. The threshold was £90,000 when we checked on 5 September 2026, confirm it on gov.uk, as it is a Budget item.

Making Tax Digital

HMRC is phasing in Making Tax Digital for Income Tax, which replaces a single annual return with quarterly digital updates for people above an income threshold, with the rollout staged by income level. Most part-time taskers are below the first stages. Check gov.uk for whether and when it applies to you, and pick your bookkeeping app with that in mind rather than switching later.

The £3,000 reporting service

HMRC's side-hustle campaign pages refer to a simpler service for people with trading income between £1,000 and £3,000, described as coming "when it's live". It was not live as at 5 September 2026. It is a change to how you report, not a new tax-free amount, and until it exists the £1,000 trigger and the 5 October deadline stand.

Do this today if you are over £1,000

Register on gov.uk. It takes fifteen minutes.
Open a separate bank account or card for the work.
Start a mileage log, for most taskers it is the largest deduction there is. See what you can claim.
Set a calendar reminder for the 31 January before your first one.

This is general information, not tax advice. Rates, thresholds and deadlines change, check gov.uk or speak to an accountant about your own circumstances.