How to register for Self Assessment for the first time

What “registering for Self Assessment” actually means

Self Assessment is HMRC’s system for declaring and paying tax on income that is not fully taxed at source (in other words, income that is not already “taken care of” through PAYE). When you register for Self Assessment for the first time, you’re telling HMRC that you need to complete a tax return, and you’re setting yourself up to file that return online (or by paper, if relevant) and pay any tax you owe.

Registration is not the same thing as filing. Registration is the “getting on the system” step: HMRC uses it to create or confirm your tax records, issue you with a Unique Taxpayer Reference (UTR), and (if you’re filing online) link Self Assessment to your HMRC online account so you can submit your return digitally. :contentReference[oaicite:0]{index=0}

Before you start: check whether you actually need to register

The most common reason people register for Self Assessment is that they are self-employed as a sole trader and have taken in more than the trading allowance (often referenced as £1,000 of gross trading income in a tax year). Other common reasons include receiving rental income, having significant untaxed income, or needing to report certain other circumstances that require a return.

Even if you are not self-employed, you can still need Self Assessment. HMRC has separate routes for registering depending on your situation (for example, self-employed vs. not self-employed). Choosing the right route matters, because it affects what form/process you use and what HMRC sets up for you. :contentReference[oaicite:1]{index=1}

Key deadline for first-time registration

If you need to complete a tax return for a previous tax year and you have not sent a tax return before (or you registered before but did not need to send one for the relevant year), you generally must tell HMRC by 5 October following the end of that tax year. Missing that “tell HMRC” deadline can lead to penalties. :contentReference[oaicite:2]{index=2}

UK tax years run from 6 April to 5 April. So, for example, if you had untaxed income in the tax year that ended on 5 April, the “tell HMRC” deadline is the following 5 October. :contentReference[oaicite:3]{index=3}

What you’ll need to register (gather this first)

Having your details to hand makes the online process much smoother. In most cases you should be ready with:

• Your full name and current address (and previous address if you’ve moved recently).

• Your date of birth.

• Your National Insurance number (if you have one).

• Contact details (email and phone).

• If you are self-employed: your business details (for example, business name if you use one, business address, and the date you started trading).

• If you are registering for something else (for example, property income): notes about when the income started and what type it is.

Once registered, you’ll also need good records so you can complete your return accurately (bank statements, invoices, receipts, summaries from platforms you sell through, mileage logs, and so on). HMRC explicitly stresses record-keeping as part of the Self Assessment process. :contentReference[oaicite:4]{index=4}

Step-by-step: registering for Self Assessment for the first time

Step 1: Use HMRC’s “check how to register” route

The simplest way to avoid ending up in the wrong process is to start at HMRC’s “Check how to register for Self Assessment” guidance and follow the path that matches your situation. This is where you choose whether you’re registering because you’re self-employed, not self-employed, part of a partnership, and so on. :contentReference[oaicite:5]{index=5}

Step 2: Create or sign in to your HMRC online account (Government Gateway)

For most people, registering online involves using an HMRC online account accessed via Government Gateway. If you already use HMRC services online (for example, to check your tax code), you may already have a Government Gateway sign-in. If you do, sign in with your existing details rather than creating a duplicate account.

If you are brand new, you’ll create a Government Gateway user ID and set up sign-in security. This is also a good moment to make sure your email address is current and secure, because HMRC is increasingly “digital by default” for communications, and you don’t want to miss important prompts or reminders. :contentReference[oaicite:6]{index=6}

Step 3: Register according to your situation

HMRC’s registration routes differ depending on why you need Self Assessment. The big split is usually:

• Self-employed (sole trader): you’re registering your self-employment and Self Assessment together.

• Not self-employed: you need Self Assessment for another reason (for example, certain untaxed income), so you register without registering a sole trader business.

• Partnership: there are additional steps and specific partnership registration requirements.

HMRC provides specific guidance for people who are not self-employed but need to register for Self Assessment, including what happens after you register and typical response times. :contentReference[oaicite:7]{index=7}

Step 4: Submit the registration and wait for your UTR (and any activation details)

After you submit your registration, HMRC will process it and issue you a Unique Taxpayer Reference (UTR) if you don’t already have one. A UTR is a 10-digit reference used to identify you in the Self Assessment system.

HMRC guidance indicates you’ll usually be contacted within around 21 days after they receive your registration (timings can vary in busy periods), and if you registered online you may be able to see your UTR sooner in the HMRC app or your personal tax account. :contentReference[oaicite:8]{index=8}

Step 5: Link Self Assessment to your account and confirm you can file online

Once you have the details HMRC provides, you’ll follow the prompts in your HMRC online account to ensure Self Assessment is available as a service. After that, you can start preparing your tax return.

If you’re planning to file online, remember the online filing deadline is typically later than the paper deadline. HMRC’s Self Assessment deadlines page sets out the key dates, including paper vs. online submission and payment timelines. :contentReference[oaicite:9]{index=9}

Paper vs online: understand the main filing and payment deadlines

Even though this article is about registration, it helps to know what you are registering yourself for. The key dates most first-timers need to be aware of are:

• 5 October (after the end of the tax year): deadline to tell HMRC you need to complete a return (often done by registering). :contentReference[oaicite:10]{index=10}

• 31 October: typical deadline for paper tax returns. :contentReference[oaicite:11]{index=11}

• 31 January: typical deadline for online tax returns and for paying the tax you owe for that tax year. :contentReference[oaicite:12]{index=12}

If you miss these deadlines, HMRC can apply penalties and interest, so building a simple calendar reminder system (even just a note in your phone) is genuinely worth it. :contentReference[oaicite:13]{index=13}

Choosing the right registration route: common first-time scenarios

You’re self-employed for the first time (sole trader)

If you started working for yourself—freelancing, running a side business, taking on paid gigs, selling goods regularly, or providing services—and your gross income from that trading activity goes over the trading allowance, you will often need to register. Be careful here: “gross” means before expenses. If you’re unsure whether your activity counts as trading, or whether