I am employed and pay tax through PAYE. Do I still need to file?

Usually not — PAYE handles most employees' tax automatically. However, you must file if you earn over £100,000, have other untaxed income, received Child Benefit with income over £60,000, or HMRC has sent you a notice to complete a return.

What happens if I miss the January deadline?

HMRC automatically issues a £100 penalty for late filing, even if you owe no tax. After 3 months, daily penalties of £10 per day (up to 90 days) apply. After 6 months, a further 5% of unpaid tax or £300 (whichever is higher) is added. After 12 months, a further 5% or £300.

Can I file Self Assessment myself or do I need an accountant?

Many people file successfully without an accountant, especially if their tax affairs are straightforward (e.g. self-employed with simple income). HMRC's online service walks you through the process. An accountant is more valuable if you have complex income sources, investments, foreign income or need tax planning advice.

What records do I need to keep?

Keep records of all income, expenses, invoices, receipts, bank statements and P60/P45 for at least 5 years after the 31 January filing deadline. HMRC can investigate returns up to 4 years back (and up to 20 years in cases of fraud).

How do I tell HMRC I no longer need to file?

If your circumstances change and you no longer meet the criteria for Self Assessment, contact HMRC to deregister. You can do this online via your Personal Tax Account or by calling 0300 200 3310. Do not simply stop filing without formally deregistering — HMRC will still expect a return.

Person filling in a tax return form on a laptop

Self Assessment Tax Return: Who Needs to File One?

6 April 2026·6 min read·

self assessmenttax returnhmrc

Most UK employees have their tax handled automatically through PAYE and never need to file a tax return. But millions of people do need to complete a Self Assessment return each year — and failing to do so on time results in automatic penalties, even if you do not owe any tax. Here is how to know if you are one of them.

Who Must File a Self Assessment Return?

HMRC requires you to complete a Self Assessment tax return if any of the following applied in the tax year:

You were self-employed (sole trader) and your income exceeded £1,000
You were a partner in a business partnership
Your income from all sources exceeded £150,000
You received untaxed income above £2,500 (e.g. rental income, overseas income)
You received rental income above £1,000 from property
You earned over £100,000 — even if employed and on PAYE
You received income from abroad that is taxable in the UK
You received Child Benefit and either you or your partner earned over £60,000
You have capital gains above the annual exempt amount (£3,000 in 2025/26)
You received dividends that exceed the Dividend Allowance (£500 in 2025/26) and take you above the basic rate band
You want to claim certain reliefs (e.g. Gift Aid at higher rate, Marriage Allowance, pension contributions beyond basic rate)
HMRC has sent you a notice to complete a return

If HMRC has sent you a Self Assessment notice, you must file — even if you believe you do not owe any tax. Ignoring the notice results in automatic penalties.

Key 2025/26 Deadlines

Self Assessment deadlines — 2025/26 tax year
Deadline	What you need to do
5 October 2026	Register for Self Assessment if filing for the first time
31 October 2026	Submit paper tax return
31 January 2027	Submit online return AND pay any tax owed
31 July 2027	Pay second Payment on Account (if applicable)

The 31 January deadline is the most important date for most people. Miss it and HMRC automatically issues a £100 fine — even if you owe no tax. The penalty increases after 3, 6 and 12 months.

The High Income Child Benefit Charge

If you or your partner earned over £60,000 and received Child Benefit, you must complete a Self Assessment return to pay back some or all of the benefit through the High Income Child Benefit Charge (HICBC). The charge was updated in April 2024 — the threshold rose from £50,000 to £60,000 and the taper now runs to £80,000 (previously £60,000), so the benefit is fully clawed back above £80,000.

Registering for Self Assessment

If you are filing for the first time, you need to register with HMRC before you can submit a return. The registration deadline for the 2025/26 tax year is 5 October 2026. HMRC will then send you a Unique Taxpayer Reference (UTR) number, which you use every year when filing.

Register online at gov.uk/register-for-self-assessment
Allow up to 10 working days for your UTR to arrive by post
Keep your UTR safe — you will need it every year
You can also use HMRC's app to manage your Self Assessment

Payments on Account

If your Self Assessment tax bill exceeds £1,000, HMRC requires you to make advance payments toward next year's bill — called Payments on Account. These are split into two instalments: 31 January and 31 July. Each is 50% of your previous year's tax bill. This can catch first-time filers by surprise, as the January payment includes both the previous year's balancing payment and the first payment on account for the current year.

How to Reduce Your Bill

Pension contributions: gross contributions reduce your adjusted net income — claim them on your return
Gift Aid: higher and additional rate taxpayers can claim the difference between their rate and basic rate
Professional subscriptions: professional body fees relevant to your employment are deductible
Working from home: if self-employed, a proportion of home costs may be deductible
Allowable business expenses: self-employed people can deduct a wide range of costs — keep records throughout the year

Frequently Asked Questions

Marcel Tonet

AAT Qualified · CeMAP Qualified · Tech & Financial Services

Marcel is an AAT-qualified accounting technician and CeMAP-qualified mortgage adviser with a career spanning technology and the UK financial services industry. He built and maintains Salary Take Home UK, updating all tax rates and thresholds each April for the new tax year.

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