Self Assessment

Register for Self Assessment by 5 October 2026

If you need to file a Self Assessment tax return for the 2025-26 tax year, you must tell HMRC by 5 October 2026. Registering is quick: the hard part is knowing whether you need to.

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Register for Self Assessment

for the 2025-26 tax year (6 April 2025 to 5 April 2026)

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Do I need to register for Self Assessment by 5 October 2026?

You must tell HMRC by 5 October 2026 if you need to file a Self Assessment return for the 2025-26 tax year. That usually means you were self-employed and earned more than £1,000, were a partner in a partnership, had to pay Capital Gains Tax, owe the High Income Child Benefit Charge outside PAYE, or had other untaxed income such as dividends or rental income. Answer the questions below to check your own situation.

Check your situation

Do I need to register?

Work through these questions about the 2025-26 tax year (6 April 2025 to 5 April 2026) to see whether you need to tell HMRC.

Do I need to register for Self Assessment?

Answer a few questions about the tax year 6 April 2025 to 5 April 2026.

Question 1

Have you already sent a Self Assessment tax return before, so you already have a UTR?

Read the whole checklist as text

  • Have you already sent a Self Assessment tax return before, so you already have a UTR?

    • Yes, I already have a UTR: You do not register again
    • Not sure: Check whether you already have a UTR
    • No: next, "In the tax year 6 April 2025 to 5 April 2026, were you self-employed as a sole trader?"

  • In the tax year 6 April 2025 to 5 April 2026, were you self-employed as a sole trader?

    • Yes: next, "Was your self-employed income more than £1,000 before expenses?"
    • No: next, "Were you a partner in a business partnership?"

  • Was your self-employed income more than £1,000 before expenses?

    • Yes: Register as self-employed
    • No: next, "Were you a partner in a business partnership?"

  • Were you a partner in a business partnership?

    • Yes: Register as a partner
    • No: next, "Did you have any income that was not taxed at source?"

  • Did you have any income that was not taxed at source?

    • Yes: You probably need to register
    • No: next, "Did you sell something that made a gain you have to pay Capital Gains Tax on?"

  • Did you sell something that made a gain you have to pay Capital Gains Tax on?

    • Yes: Register for Self Assessment
    • No: next, "Do you or your partner get Child Benefit, with one of you having income over the High Income Child Benefit Charge threshold that is not taxed through PAYE?"

  • Do you or your partner get Child Benefit, with one of you having income over the High Income Child Benefit Charge threshold that is not taxed through PAYE?

    • Yes: Register for Self Assessment
    • No: next, "Are you a company director?"

  • Are you a company director?

    • Yes: Being a director alone does not mean you must file
    • No: You probably do not need to register

Who registers

Who has to register for Self Assessment

HMRC does not automatically know when your circumstances change, so it is down to you to tell them. You need to register for Self Assessment if any of these applied to you in the tax year:

  • You were self-employed as a sole trader and earned more than £1,000 before expenses.
  • You were a partner in a business partnership.
  • You had to pay Capital Gains Tax on a gain.
  • You had to pay the High Income Child Benefit Charge and it was not collected through PAYE.
  • You had untaxed income, such as rental income, tips or commission, savings interest, dividends or income from abroad.

If your only self-employed or property income was £1,000 or less before expenses, the trading and property allowances mean you can usually earn up to £1,000 tax-free in each without registering for that income alone. If you have both types of income, you get a £1,000 allowance for each. If you are not sure where you stand, GOV.UK has a short checker that asks about your situation and tells you whether you need to register.

How to register

How to register, step by step

  1. 1Go to gov.uk and start the registration for your situation: sole trader, partner, or another reason.
  2. 2Set up a Government Gateway account (your HMRC online account) if you do not already have one.
  3. 3Give your National Insurance number and contact details.
  4. 4If you are self-employed, give the date you started and your business details.
  5. 5Wait for your UTR to arrive by post, usually around 15 days later. It takes longer if you live overseas.

Registering and filing are two different things. Registering just tells HMRC that you need to file. The return itself, with your income and any tax due, is due separately by 31 January.

Key dates

The 2025-26 tax year at a glance

Registering is one date among several. Here is where it sits against the rest of the tax year.

  1. Tax year ends

    The 2025-26 tax year finishes.

  2. Register for Self Assessment

    Tell HMRC you need to file a return, if you have not already registered.

  3. Paper return deadline

    The deadline for a paper Self Assessment return.

  4. Online return and payment deadline

    File online and pay what you owe, plus your first payment on account if it applies.

  5. Second payment on account

    The second of two advance payments towards next year's tax bill, if you make them.

Missed the deadline

Missed 5 October? What to do now

If you needed to register for a tax year and missed the 5 October deadline, register now. Waiting makes it worse: the penalty for failing to notify HMRC in time is a percentage of the tax you owed and paid late (HMRC calls this the “potential lost revenue”). How much depends on whether HMRC think it was deliberate, and whether you told them before they found out.

Your situationPenalty range
Non-deliberate, you tell HMRC first, within 12 months0% to 30%
Non-deliberate, you tell HMRC, 12 months or more after10% to 30%
Non-deliberate, HMRC find out first, within 12 months10% to 30%
Non-deliberate, HMRC find out first, 12 months or more20% to 30%
Deliberate, depending on concealment and whether prompted20% to 100%

If you have a reasonable excuse for a non-deliberate failure to notify, HMRC will not charge you a penalty at all. Telling HMRC yourself, before they find out, is always the better route.

Directors

Directors: do you need to file?

Being a company director does not by itself mean you must file a Self Assessment return. GOV.UK's guidance says you may need to complete one if, for example, you receive dividends from your company, or you have any other untaxed income in addition to your director's salary.

A salary under the personal allowance plus dividends on top: probably yes, you need to register and file, because the dividends are untaxed income. A salary taxed only through PAYE, with nothing else on top: you may not need to. If you are not sure which side of that line you sit on, GOV.UK's checker or our guide for directors can help.

After you register

What happens after you register

HMRC posts your UTR to you, usually within around 15 days. Once it arrives, set up your online account if you have not already, and keep records of your income and expenses through the year. Your return is due by 31 January, online, covering the tax year that has just ended.

If your tax bill is large enough, HMRC may also ask for payments on account: two advance payments towards next year's bill, on top of what you owe for the year just gone. See our guide to payments on account for how that works.

Where Finn helps

Finn keeps your books ready for filing

Finn does not register you for Self Assessment and does not file your return. It keeps your records up to date all year, so when you or your accountant come to file, the numbers are already there.

Try Finn free for 14 days
  • Sole trader income and expenses kept up to date as receipts and statements come in
  • Salary and dividends tracked, with the split worked out for you
  • Deadline reminders for your tax and company dates, so nothing sneaks up on you
  • Plain-English answers about your own numbers, by chat or voice

Questions

Registering for Self Assessment, answered

Do I need to do a Self Assessment tax return?

You need to file if you were self-employed and earned more than £1,000 before expenses, were a partner in a business partnership, had to pay Capital Gains Tax, had to pay the High Income Child Benefit Charge outside PAYE, or had untaxed income such as rental income, dividends, savings interest, tips, commission or income from abroad. If you are not sure, GOV.UK has a short checker.

How do I register for Self Assessment, or as self-employed?

Register online at gov.uk. You will need your National Insurance number, contact details, the date you started self-employment if that applies, and your business details. HMRC posts your Unique Taxpayer Reference (UTR) about 15 days later, longer if you live overseas. Registering only tells HMRC you need to file: the return itself is a separate step, due by 31 January.

Do directors need to do a Self Assessment tax return?

Not automatically. GOV.UK says you may need to file if you receive dividends from your company or have any other untaxed income on top of your director's salary. If your only income is a salary taxed through PAYE, you may not need to.

I'm a director with no other income. Do I still need to register?

If your only income is a salary taxed through PAYE, with no dividends or other untaxed income, GOV.UK's guidance suggests you may not need to file. Taking any dividends at all, even a small amount alongside a low salary, is untaxed income, and that generally means you do need to register.

Do I need to declare dividends on my Self Assessment return?

Yes. Dividends from your own company count as untaxed income, which is one of the reasons GOV.UK lists for needing to file a Self Assessment return.

What happens if I miss the 5 October deadline?

Register as soon as you can. The penalty for failing to notify HMRC on time is a percentage of the tax you owed and paid late, and it depends on whether HMRC think it was deliberate and whether you told them before they found out. Telling HMRC yourself, before they find out, keeps the penalty lowest, as low as 0% in some non-deliberate cases. If you have a reasonable excuse for a non-deliberate failure to notify, HMRC will not charge a penalty.

How long does it take to get a UTR?

You'll usually get your UTR by post around 15 days after you register. It takes longer if you live overseas.

What is the difference between registering and filing?

Registering tells HMRC that you need to file a return. It does not submit any figures. The return itself, with your income and any tax due, is a separate step, due online by 31 January (or 31 October on paper).

Sources, checked on

General guidance, not advice for your situation. Rules change: always check the GOV.UK page before you act.

Keep your books ready for whatever Self Assessment throws at you

Finn keeps your records up to date all year, so when it is time to file, the numbers are already there.

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