How to Register for Self Assessment with HMRC [Complete Guide]

If you earn money outside of a standard PAYE salary – whether through freelancing, self employment, rental income, or a side hustle – registering for Self Assessment correctly is essential to staying compliant and avoiding unnecessary penalties.

This guide explains how to register for Self Assessment with HMRC, who needs to register, when to register, and what happens after registration.

Whether you’re newly self employed or filing a Self Assessment tax return for the first time, this breakdown will help you prepare with confidence.

Key takeaways

• Not everyone needs to register for Self Assessment
  Registration is required only in certain cases. If all income is taxed through PAYE or under certain thresholds, registration may not be necessary.
• Registering early is crucial
  Delaying registration can lead to potential penalties, while early registration helps you avoid stress and last-minute complications.
• There are different registration routes depending on income type
  Self employed individuals register online via a Government Gateway account, non-self employed individuals use form SA1, and partners in a business partnership must register both the partnership and individually.
• Making Tax Digital (MTD) changes reporting for some taxpayers
  From 2026, sole traders and landlords with income above £50,000 must keep digital records, use HMRC-approved software, and submit quarterly updates. This gradually expands to lower thresholds in 2027 and 2028.
• Registration is usually a one-time process
  Once registered, you remain on Self Assessment until HMRC confirms otherwise. Notify HMRC if your circumstances change to avoid unnecessary returns or other tax issues.

What is Self Assessment?

Self Assessment is HMRC’s system for collecting tax from people whose income isn’t fully taxed automatically. Instead of HMRC calculating your tax for you, you report your income, expenses, and allowances, and HMRC then confirms how much tax you owe (or whether you’re due a refund).

The UK tax year runs from 6 April to the following 5 April. Each year, you submit a tax return covering that period and settle any tax owed by the following 31 January.

Who needs to register for Self Assessment?

Not everyone in the UK needs to file a tax return. However, if any of the situations below apply to you, registration is likely required.

You need to register if you:

• Are self employed or a sole trader
• Earned more than £1,000 from self employment or side income
• Have rental income from a UK or overseas property
• Receive foreign income not taxed at source
• Earned dividends or interest above tax-free allowances
• Made capital gains, such as selling shares or property
• Need to pay the High Income Child Benefit Charge
• Are a company director (in certain cases)
• Receive income from crypto assets, depending on activity

You may not need to register if:

• All your income is taxed through PAYE
• Your only self employed income is under £1,000
• You only receive tax-free income (e.g. ISAs)

If you’re unsure, it’s important to confirm your registration requirements early rather than assume you don’t need to register.

In the UK, many HMRC obligations are triggered by turnover, business activity, or legal structure – not by tax actually owed. This means you can be required to register and report even if your final tax bill is £0.

Failing to register when required can still lead to penalties for late notification or non-compliance.

Why registering early matters

One of the most common mistakes people make is postponing registration. Unlike filing a tax return, registration has its own deadline, and HMRC needs time to process it.

Here’s why you should register as soon as possible:

• HMRC sends your Unique Taxpayer Reference (UTR) by post
• This can take 2–3 weeks
• You can’t file your tax return without a UTR

Leaving registration until January may cause unnecessary stress, especially if something goes wrong.

Before you start: Key details and Self Assessment deadlines

Before registering, gather the following details to avoid delays:

• National Insurance number
• Full legal name
• Date of birth
• Current address
• Email address
• Reason for registering (self employment, rental income, etc.)
• Start date of your self employment or untaxed income

Having everything ready makes the process much smoother – and so does knowing your timelines.

Here are the key deadlines for Self Assessment you should be aware of:

For example, if you earned self employed income during the 2025–26 tax year (ending 5 April 2026), you must register by 5 October 2026. Your tax return must be filed by 31 October 2026 (paper) or 31 January 2027 (online), and any tax owed must be paid by 31 January 2027.

Step-by-Step: How to register for Self Assessment with HMRC

The way you should register for Self Assessment depends on why you need to file a tax return. HMRC uses different routes for different types of income and business structures.

Below are the three core registration options, explained step by step:

Option 1: If you’re self employed or a sole trader

This is the most common route and applies if you work for yourself and aren’t part of a partnership. Here’s what you need to do:

Step 1: Create a Government Gateway Account

To register online and manage your taxes, you’ll need a Government Gateway ID. This is HMRC’s central login system for individuals and businesses.

During setup, you’ll be asked to:

• Create login details
• Verify your identity
• Link your account to HMRC services

Once created, your Government Gateway account will be used for:

• Filing Self Assessment tax returns
• Paying Income Tax and National Insurance
• Viewing HMRC letters and messages
• Managing future tax filings and updates

If you already have a Government Gateway account (for example, from a previous tax return or VAT registration), you can reuse it.

Step 2: Register as self employed

When you register as self employed, HMRC automatically:

• Registers you for Self Assessment
• Registers you for Class 2 National Insurance contributions

As part of the registration, you’ll provide:

• Your business start date
• The nature of your work or trade
• Your personal details

This step formally tells HMRC that you’re responsible for reporting your own income and expenses.

Step 3: Receive your UTR

After HMRC processes your registration, they’ll send your UTR by post.

Key things to know about your UTR are:

• It’s a 10-digit number, and it’s typically followed by the letter ‘K’ (payment reference for Self Assessment)
• You’ll use it every year when filing tax returns
• You’ll need it to activate Self Assessment online
• You can’t submit a tax return without it

UTRs usually arrive within 2 to 3 weeks. If you haven’t received yours after three weeks, you should contact HMRC to check the status of your registration.

Option 2: If you’re not self employed (SA1 Form)

If you don’t work for yourself but still have income that isn’t taxed automatically, you’ll register for Self Assessment using form SA1.

This route applies if you earn income such as:

• Rental income from property
• Capital gains from selling assets
• Foreign income
• Taxable savings or dividends above allowances
• Other untaxed income

You can submit form SA1 in one of two ways:

• Online, using your Government Gateway account (recommended)
• By post, which takes longer to process

Once HMRC processes your SA1 form, they’ll issue your UTR by post, just as they would for a self employed registration.

Option 3: If you’re part of a partnership

If you’re in a business partnership, the registration process has two parts: one for the partnership itself and one for each partner.

Step 1: Register the partnership

One partner (usually the nominated partner) must register the partnership as a whole with HMRC. This creates a partnership tax record and allows the partnership to file its annual partnership tax return.

When registering the partnership, HMRC will issue:

• A UTR for the partnership
• Separate UTRs for each partner (if they don’t already have one)

These UTRs allow each partner to file their individual Self Assessment tax returns correctly.

Step 2: Register each partner for Self Assessment

Each individual partner must also be registered for Self Assessment in their own name.

This ensures that:

• Each partner can report their share of profits
• Income is taxed correctly at an individual level

Without individual registration, partners would be unable to submit their personal returns or be liable for their share of tax.

For all digital scenarios: Activating Self Assessment online

Regardless of which route you use, once you receive your UTR, you’ll need to activate the Self Assessment service in your Government Gateway account.

This process involves:

1. Signing in to your Government Gateway account
2. Adding Self Assessment to your list of services
3. Entering your UTR
4. Confirming activation

Without activating Self Assessment online, you won’t be able to submit your tax return digitally and may be forced to file by post or contact HMRC for assistance.

Incoming changes: How Making Tax Digital (MTD) fits in

From 2026 onwards, some taxpayers will also need to comply with Making Tax Digital for Income Tax Self Assessment (MTD for ITSA).

If you’re a sole trader or a landlord and your qualifying income exceeds the relevant threshold, you may be required to:

• Keep digital records
• Use HMRC-recognised software
• Submit quarterly digital updates during the year
• Complete a final declaration instead of a single traditional annual return

If MTD applies to you, this changes how and when you report information, but it doesn’t change the fact that you must first be registered for Self Assessment.

Here are the MTD thresholds for Income Tax:

Taxpayers below the MTD thresholds should continue to follow the usual Self Assessment process.

Do you need to register every year?

No. Registering for Self Assessment is usually a one-off step, not something you repeat annually.

Once you’re registered:

• You remain registered unless HMRC tells you otherwise.
• You’ll normally be expected to submit a tax return each year while you have taxable income.
• In some cases, HMRC may confirm that you no longer need to file, but until they do, the obligation remains.

If your circumstances change – for example, you stop trading, close a business, or no longer receive untaxed income – it’s important to inform HMRC as soon as possible. This helps prevent unnecessary filing requests, penalties, or reminder letters for returns you no longer need to submit.

How ANNA can help you handle Self Assessment with ease

Managing Self Assessment doesn’t have to mean juggling spreadsheets, receipts, and deadlines on your own.

Whether you’re registering for the first time or looking for an easier way to manage ongoing tax obligations, ANNA helps simplify Self Assessment, so you can focus on running your business, not chasing paperwork.

Here’s how ANNA makes Self Assessment efficient:

• Automatic income and expense tracking – Your business income and spending are tracked directly through your ANNA business account, so your records stay up to date without manual input.
• Receipt capture that actually stays organised – Snap receipts as you go, and ANNA will automatically categorise and organise them, helping you maintain accurate digital records all year round.
• Built-in support for MTD reporting – ANNA prepares and submits your quarterly updates and end-of-period statements in line with HMRC’s requirements. ANNA will also file your 2026-27 Self Assessment for free, and if you’ve already filed with alternative software, you’ll get a full refund when you switch.
• Real-time tax estimates – See what you’re likely to owe as you earn, rather than finding out months later, and avoid unpleasant surprises at the deadline.
• A dedicated Tax Pot for peace of mind – Set money aside as you go, so your tax bill is already covered when it’s time to pay.
• Less admin, fewer deadlines to worry about – With everything in one place, Self Assessment becomes a steady, manageable process instead of a once-a-year scramble.

Ready to take the stress out of Self Assessment? Sign up for ANNA today and stay on top of your taxes effortlessly.