How to Register as Self-Employed with HMRC (Step-by-Step)

Do you need to register as self-employed?

If you are earning money from freelancing, contracting, selling goods or services, or running any kind of trade outside of PAYE employment, HMRC generally expects you to register for Self Assessment as a sole trader. This applies whether the work is your main income or something you do alongside a job.

There is one exception worth knowing: the trading allowance lets you earn a small amount from self-employment each tax year without needing to register or pay tax on it, provided you have no other reason to file a return. If your income is close to that threshold, it is worth checking your position carefully rather than assuming you are exempt — and once you go over it, registration is required.

If you are unsure whether your activity counts as "trading" in HMRC's eyes — as opposed to, say, occasionally selling personal possessions — a quick conversation with a bookkeeper or accountant is far cheaper than guessing wrong.

Step 1 — Check you have the right information ready

Before you start the online registration, have the following to hand:

• Your National Insurance number
• Your full name, date of birth, and home address
• Your business trading name (or your own name, if you are trading under it)
• The date your self-employment started
• A description of what your business does
• An email address and phone number HMRC can use to contact you

Step 2 — Register online with HMRC

Go to gov.uk and register for Self Assessment as a sole trader. If you do not already have a Government Gateway user ID, you will create one as part of this process — keep the ID and password somewhere safe, as you will need them every year to file your return.

The registration form asks about your business activity, the date you started trading, and your contact details. Once submitted, HMRC processes the registration and sets up your Self Assessment record.

Step 3 — Wait for your Unique Taxpayer Reference (UTR)

After registering, HMRC posts you a letter containing your ten-digit Unique Taxpayer Reference (UTR). This is the number you will use every year to file your Self Assessment tax return, and you will also need it for things like applying for a mortgage as a self-employed person. For a full explanation of what it is and how to find it if you lose it, see our guide to the UTR number.

Registering by post rather than online is also possible using form CWF1, but it takes longer and most sole traders find the online route quicker.

Step 4 — Know your deadline

You must register for Self Assessment by 5 October following the end of the tax year in which you started trading. For example, if you started self-employment at any point between 6 April 2026 and 5 April 2027, you must register by 5 October 2027.

Missing this deadline can result in a penalty if it leads to you filing or paying late. There is no advantage to delaying registration — the sooner you register, the sooner your UTR arrives, and the more time you have to get your bookkeeping in order before your first filing deadline.

Registering while also employed

You can be employed under PAYE and self-employed at the same time. If you have a side income alongside your job, you still need to register for Self Assessment once your self-employed earnings are enough to require it. Your employment income continues to be taxed through PAYE as normal; your self-employment income is declared and taxed separately through your tax return, alongside anything already collected via PAYE.

What happens after you register

Once your UTR arrives, the practical work begins:

• Set up a system for recording income and expenses from day one — ideally cloud accounting software rather than a shoebox of receipts
• Open a separate business bank account to keep transactions clean (see our guide to choosing a business bank account)
• Understand your VAT position if your turnover is likely to grow quickly
• Set aside money for tax as you earn, rather than waiting until January

Our financial checklist for starting a business in the UK walks through each of these steps in more detail.

Common mistakes to avoid

The most common mistakes new sole traders make around registration are: leaving it until close to the 5 October deadline and then scrambling; losing the letter containing their UTR and not knowing how to retrieve it; and assuming that registering as self-employed also registers them for VAT (it does not — VAT registration is a separate step, required once your taxable turnover crosses the registration threshold).

Getting registration right at the start makes everything that follows — your first tax return, your UTR, your bookkeeping — considerably less stressful.