Self-assessment for beginners

What is self-assessment?

Self-assessment is a way of telling the tax office – HM Revenue & Customs (HMRC) – about your income, so you can pay the right amount of tax.

The first key thing to understand about self-assessment is that it's backward-looking. Each year, you have to submit a tax return for the previous full tax year.

1. Check if you need to complete self-assessment

Most UK taxpayers have their taxes deducted automatically from their wages or pensions, and don't need to file self-assessment tax returns – but there are millions who do.

You may need to submit a tax return if ANY of the following applied to you in the 2024/2025 tax year (6 April 2024 to 5 April 2025):

• You were self-employed and your income was over £1,000. Thanks to the trading allowance, you can earn up to £1,000 working for yourself each tax year without having to declare this to HMRC – above this threshold, you need to undertake self-assessment.
  
  If you earned £1,000 or less, you may still need to submit a self-assessment return if you want to pay 'class 2' National Insurance contributions voluntarily to protect your entitlement to the state pension and certain benefits.

• You earned over £1,000 from property or land. The exact thresholds here vary depending on your circumstances, and in some cases you can earn more than this without having to complete self-assessment. For example, if the income came from renting out a room in your main home (having a lodger), you can earn up to £7,500 under the Government's 'Rent a Room' scheme without having to declare it. For more info, see Property income rules.

• You earned £10,000 or more from savings interest (excluding from savings in ISAs, which are tax-free).

• You earned £10,000 or more from investments or dividends (excluding from investments in ISAs).

• You earned £2,500 or more from tips, commission or any other 'additional income'.

• You got income from abroad – including pensions.

• You got income from a trust.

• You need to pay Capital Gains Tax. You may have to pay this if you sold or gave away personal possessions worth £6,000 or more (apart from your car or main residence), or some other assets such as shares in a company or a holiday home. The rules are complex – for more info, see Gov.uk.

• You worked for a client through an intermediary (such as a limited company or partnership) and you have a student loan. This is known as 'off-payroll working' or contracting.

• You accessed your private pension early (before age 55 in most cases). Though there are some exceptions here, including where you're retiring due to ill health. See Can I withdraw from my pension early?

• You exceeded the annual allowance for paying into your pension. See How much you can put into a pension.

• You held a work position that affects how you're taxed. These are (for historical reasons that we won't get into here): religious minister (of any faith or denomination); Lloyd's underwriter; examiner, exam moderator or invigilator; share fisher (a fishing industry worker who gets all or part of their pay from a share of the boat's profits).

• You filed a self-assessment tax return for the 2023/24 tax year – unless you've already told HMRC you no longer need to or HMRC has told you not to.

Important: The self-assessment criteria is complex and changes fairly regularly, so use the above list as an indicator rather than a rigid checklist. If you're in any doubt, use HMRC's online tool to check if you need to file for self-assessment or ask HMRC.

Recent changes mean some may no longer need to file a tax return

Some of the rules in place for previous tax years have changed for 2024/25, taking some people out of the self-assessment system. This impacts:

• High earners. For the 2023/24 tax year, those with taxable income above £150,000 were required to undertake self-assessment. This is no longer the case for 2024/25, so you don't have to submit a tax return just because your income exceeds a certain level (though of course you may still need to for other reasons, as listed above).
  
  If your income was the ONLY reason you had to complete a tax return for 2023/24, you should have gotten a letter from HRMC telling you that you don't need to file one for 2024/25. If you didn't get one, contact HMRC directly to check.

• Child Benefit recipients earning £60,000+. Under the High Income Child Benefit Charge, if you or your partner earn more than a certain amount – currently £60,000 a year – you have to start repaying the benefit. Until very recently, the only way to do this was through self-assessment.
  
  However, following the launch of a new service in September 2025, you may now be able to pay the charge by having it automatically deducted from your salary instead (meaning you could potentially stop filiing for self-assessment). For full info, see Child Benefit changes.

2. Register for self-assessment as soon as possible

If you're new to self-assessment, you need to register with HMRC first and get a Unique Taxpayer Reference (UTR). The deadline to do this was technically 5 October 2025 – though you should still be OK if you do it now (the longer you leave it, the riskier it gets).

Your UTR is a 10-digit code sometimes called your 'tax reference'. You need a UTR to sign in to the online self-assessment platform and to submit your tax return.

You should get your UTR in the post within three weeks of registering. If it's been a while since your registration request and you haven't gotten your UTR in the post, check the HMRC app or your online HMRC account – you may be able to see it there sooner.

3. Gather your paperwork

Before you start your tax return, you'll need to gather some documents. Depending on your circumstances, this could include:

• If you're employed – payslips, tax notices from HMRC, your P60 (which you get from your employer after the end of the tax year), P11D (which your employer uses to notify HMRC about any benefits you get) or P45 (which your employer should give you when you leave a job);

• If you're self-employed – receipts, invoices and any other records of both your income and any business expenses;

• If you have property income – receipts, invoices or statements from lettings agents;

• If you have other income – statements from providers (such as savings or investment providers or private pension firms);

• Helpful for everyone, regardless of where your income comes from – bank or building society statements, details of pension contributions.

You don't need to send any of this paperwork to HMRC, unless it asks you to – but it's important to keep it as evidence of the information in your tax return.

How long to keep records

• If you're self-employed: you must keep records – whether paper or digital – for at least five years after the tax return deadline for the relevant year. For example, if you send your 2024/25 tax return online by 31 January 2026, you must keep your records for this until at least the end of January 2031.

• For everyone else: the official rule is that you must keep records for at least 22 months (just under two years) after the end of the tax year – though see Martin's old blog for why it's often a good idea to keep bank statements and other personal finance documents for as long as you can.

4. Fill out your tax return

Once you've gathered the information you need, you can (in almost all cases) complete and file your tax return online. You don't need to complete the whole online form in one go – you can save your progress and come back to it later.

Some people, including religious ministers, those who live abroad, and those who get income from a trust, can't use the online service and may have to submit a paper return instead.

If you're able to, completing your return online means you have an extra three months to file – the online deadline for the 2024/25 tax year is 31 January 2026, while the paper deadline is 31 October 2025.

Free help with self-assessment

If you're struggling to complete the form, here are some free options you can try:

• Check the official guidance. HMRC's online resources cover every section of the form (employment, self-employment, property and so on). Prefer to watch rather than read? HMRC also publishes videos and webinars.

• Contact HMRC directly. You can use its digital assistant and webchat or call its helpline on 0300 200 3310 (lines open Monday to Friday, 8am to 6pm).

• On a low income? Ask a specialist charity for one-on-one help. The TaxAid charity, for example, offers free, independent advice if you're unable to pay for professional assistance.

Is it worth paying someone to complete your tax return?

It really depends. If your circumstances are fairly simple – you're employed and just need to report extra income from savings or investments, say – completing your self-assessment can be pretty straightforward. The online form guides you through step-by-step, and if you start early (in other words, now!) you have plenty of time to raise any queries with HMRC before the 31 January deadline.

But if your situation is more complicated, or you just find the process too intimidating to tackle on your own, it could be worth paying a professional for help. If you decide to go down this route, make sure to check the following:

• Their qualifications and experience – are they a member of a professional body? This could include the Institute of Chartered Accountants in England and Wales (ICAEW) or the Association of Accounting Technicians.

• What service is being offered – is it form-filling, advice or both? Tax professionals can help by giving you advice on what expenses you're allowed to claim, what reliefs you can get and so on – but don't assume this is included automatically. It's also worth checking what (if any) ongoing support is included.

• How do the fees work – is it a one-off fixed fee or an hourly rate? Make sure this is clear upfront, so you don't get hit with unexpected charges later on in the process.

5. Pay the tax due

Once you've submitted your self-assessment tax return, you'll get a statement (bill) summarising what you owe and the payments you need to make. Watch HMRC's video to see what this looks like and how it works.

For the 2024/25 tax year, you need to pay any remaining tax you owe by 31 January 2026 – this is known as a 'balancing payment'.

Once you're in the self-assessment system, you'll usually also have to make advance payments towards next year's bill – these are known as 'payments on account' and are based on how much tax you had to pay the previous year. Here's a simplified example to show you how this works in practice: