The UK does not issue a single document called a Tax Identification Number (TIN). Instead, HMRC and international tax frameworks use different reference numbers depending on your situation. For most employed individuals, the National Insurance number (NINO) acts as the UK TIN. For sole traders, landlords, and anyone registered for Self Assessment, it is the Unique Taxpayer Reference (UTR).
For limited companies, it is the company UTR for Corporation Tax purposes, or the Company Registration Number in certain reporting regimes. When a foreign bank, employer, or official form asks for your UK TIN, the right answer depends on who you are and what the form is for.
What is a Tax Identification Number?
A Tax Identification Number is a reference code that a country’s tax authority uses to match every person, business, or entity to their tax records. Think of it as a unique account number for your relationship with the tax system, it makes sure that when HMRC receives a payment, a return, or information about your income, it links that data to the right person and not to anyone else.
In countries like the United States, there is one system: individuals get a Social Security Number (SSN), businesses get an Employer Identification Number (EIN). Together, these form a single national TIN framework. The UK takes a different approach. Rather than creating one unified number, HMRC has always used purpose-built identifiers for different tax functions and those identifiers collectively serve the role that a single TIN performs elsewhere.
The term TIN became more prominent in the UK when the OECD launched the Common Reporting Standard (CRS) in 2014. CRS requires financial institutions around the world to collect TINs from account holders and report them to their country’s tax authority. When UK banks began asking British customers for their TIN on account forms, many people had no idea what to write.
HMRC’s manual IEIM902330 addresses this directly. It confirms that the UK does not issue a standalone TIN, but that for most UK-resident individuals the National Insurance number serves this function. For companies, the Unique Taxpayer Reference (UTR) is the number that matches the OECD definition.
What Counts as a Tax Identification Number in the UK?
The right number to use as your UK TIN depends entirely on your tax status and the context in which you are being asked. The table below covers every main situation:
| Who You Are | Your UK TIN Equivalent | Format | Issued By | Use |
|---|---|---|---|---|
| Employed individual | National Insurance number (NINO) | AB 12 34 56 C | DWP at birth or on application | PAYE, personal tax, social security |
| Self-employed sole trader | Unique Taxpayer Reference (UTR) | 10 digits | HMRC on Self Assessment registration | Self Assessment, income tax returns |
| Landlord / investor | UTR (if filing Self Assessment) | 10 digits | HMRC | Self Assessment returns |
| Limited company | Company UTR | 10 digits | HMRC on company registration | Corporation Tax, CRS/FATCA forms |
| VAT-registered business | VAT Registration Number (VRN) | GB + 9 digits | HMRC on VAT registration | VAT returns, invoices, EC sales lists |
| Company — platform reporting | Company Registration Number (CRN) | 8 digits | Companies House | HMRC Digital Platform Reporting (2026) |
| Partnership | Partnership UTR | 10 digits | HMRC | Partnership tax return (SA800) |
Source: HMRC manual IEIM902330, OECD CRS United Kingdom country sheet (consulted October 2026), HMRC Digital Platform Reporting guidance July 2026
Is a National Insurance Number a Tax Identification Number?
Yes, for individuals, the National Insurance number is the closest thing the UK has to a TIN. HMRC’s own manual says it is the number that a UK-resident individual should provide when a foreign institution, a CRS self-certification form, or a cross-border reporting obligation asks for a TIN.
The NI number was originally created to track National Insurance contributions and entitlement to state benefits, not purely for income tax. But because it is assigned to every UK resident individually and because HMRC links it to PAYE records, Self Assessment registrations, and personal tax accounts, it functionally serves as the personal TIN for most people.
What Does a National Insurance Number Look Like?
The NI number follows a fixed format that HMRC will never deviate from. Understanding the format helps you confirm whether a number someone claims is a valid NINO or whether something has gone wrong:
| Part | Example | What It Represents |
|---|---|---|
| Prefix letters | AB | Two letters — never starts with D, F, I, Q, U, V; second letter never D, F, I, O, Q, U, V |
| First digit pair | 12 | Sequential number assigned by the National Insurance system |
| Second digit pair | 34 | Sequential continuation |
| Third digit pair | 56 | Sequential continuation |
| Suffix letter | C | Can be A, B, C, or D — related to original NI contribution year grouping |
| Full number | AB 12 34 56 C | Always written with spaces between each pair for readability |
A valid NI number always contains exactly nine characters when the spaces are removed — two letters, six digits, and one letter. It is never entirely numeric. If someone gives you a number that is all digits, it is not a National Insurance number.
Your NI number stays with you for life. It does not change when you change jobs, move house, get married, or become self-employed. It is issued once by the Department for Work and Pensions, usually shortly before your sixteenth birthday or when you first apply to work or claim benefits in the UK.
Your National Insurance number is one of the most sensitive pieces of personal data you hold. HMRC or the Department for Work and Pensions will never call you out of the blue and ask you to confirm it. If anyone contacts you unexpectedly asking for your NI number, treat it as a potential fraud attempt.
Is a UTR Number the Same as a Tax Identification Number?
For self-employed individuals, limited companies, landlords, and anyone filing Self Assessment returns, yes, the Unique Taxpayer Reference (UTR) is the number that functions as the UK TIN for tax return and business purposes.
HMRC issues a UTR to you automatically when you register for Self Assessment. It is also issued to every company when it is incorporated and registered with HMRC for Corporation Tax. The UTR is the primary reference number HMRC uses to track your returns, payments, and correspondence.
What Does a UTR Number Look Like?
| Feature | Detail |
|---|---|
| Length | Always exactly 10 digits — no letters |
| Example | 1234567890 |
| Where used | Self Assessment returns, Corporation Tax returns, PAYE for employers, pension scheme registration, CRS/FATCA international forms |
| Issued when | On registering for Self Assessment (sole traders/individuals) or on company incorporation (companies) |
| One or many? | Each person or entity gets one UTR. A sole trader has one personal UTR. A limited company they own has a separate company UTR. |
| On forms | Sometimes written as ‘tax reference’, ‘taxpayer reference’, or ‘HMRC reference’ — it is the same number |
A UTR is always ten digits, no letters, no spaces. This distinguishes it immediately from a National Insurance number (which contains letters) and a VAT number (which begins with GB). If a form asks for your tax reference and you are self-employed or a company director, this is the number to reach for.
If you are both employed and self-employed, as many people running a small business alongside a PAYE job are you have both a NI number and a UTR. Your NI number identifies you to HMRC as an individual. Your UTR identifies your Self Assessment record specifically. You will use both at different points when dealing with HMRC.
When a foreign bank, investment platform, or international employer asks for your UK TIN as part of a CRS or FATCA self-certification, the OECD’s United Kingdom country sheet confirms the UTR is the relevant identifier for companies and entities. For individuals without a UTR, the NI number should be provided instead.
How Do You Find Your Tax ID Number in the UK?
The answer depends on which number you need. The table below shows where to look for each one:
| Tax Reference | Where to Find It |
|---|---|
| NINO | Payslip, P60, P45, National Insurance card (if issued), HMRC letters, Personal Tax Account at gov.uk |
| UTR | HMRC welcome letter (SA250) sent when you register for Self Assessment, Self Assessment tax return, any HMRC letter about your Self Assessment, HMRC online account at gov.uk |
| Company UTR | First letter from HMRC after company registration, Corporation Tax correspondence, accounting software linked to HMRC |
| VAT number | VAT registration certificate (VAT4), any VAT return, VAT account in HMRC’s online services |
| CRN | Companies House registration letter, any Companies House correspondence, company bank account documentation |
How to Find Your National Insurance Number
Your NI number appears in several places you likely already have:
- On your payslip, usually listed alongside your employee reference
- On your P60 at the end of each tax year
- On any P45 you received when leaving a previous job
- On letters from HMRC or the Department for Work and Pensions
- In your Personal Tax Account at gov.uk, log in with your Government Gateway credentials
If you cannot find it anywhere, you can request a reminder using the ‘Find a lost National Insurance number’ service on gov.uk. HMRC will send it to your registered address by post. You cannot get your NI number over the phone for security reasons.
How to Find Your UTR Number
Your UTR is found in all HMRC correspondence relating to your Self Assessment or Corporation Tax account:
- The SA250 welcome letter HMRC sends when you first register for Self Assessment
- Any Self Assessment return you have previously filed — it appears at the top of the return
- Your HMRC online account under the Self Assessment section
- Any letter about your annual tax bill, payment on account, or penalty notice
- Your accounting software, if it is connected to HMRC through the Government Gateway
If you are a limited company director, your personal UTR and your company UTR are different numbers. Your personal UTR relates to your own Self Assessment return. Your company UTR relates to the company’s Corporation Tax return. Both will be in HMRC correspondence, but they are issued separately and cannot be used interchangeably.
What Does a UK TIN Number Look Like?
Because the UK uses multiple identifiers rather than one, the format of the number you use as a TIN will differ depending on your situation:
- National Insurance number format: Two letters, six digits, one letter — example: AB 12 34 56 C. Always presented with spaces for readability. Nine characters total when spaces are removed.
- UTR format: Ten digits, no letters, no spaces — example: 1234567890. Sometimes written with a slash before the last three digits for readability: 1234567/890.
- VAT number format: Starts with the country prefix GB followed by nine digits — example: GB 123 4567 89. Some EU-format numbers add branch identifier digits for larger businesses.
- Company Registration Number (CRN) format: Eight digits for most companies — example: 12345678. Some older or Scottish companies have a two-letter prefix such as SC or NI followed by six digits.
If someone tells you they have a UK TIN and shows you a number that does not match any of these formats — for example, a number beginning with a letter other than GB that does not follow the NI number pattern — it is worth questioning whether the number is correct.
Why Does Your TIN Matter as a Self-Employed Person or Business Owner?
For business owners and sole traders, getting the right reference number on the right document is a practical issue that comes up regularly:
- Filing your Self Assessment return: Your 10-digit UTR is required on every Self Assessment submission. Filing without it or with an incorrect UTR will cause the return to be rejected or misfiled.
- Registering for VAT: When you register for VAT, HMRC links your VAT account to your UTR. Your VAT number is separate but the UTR is the underlying reference that connects it to your tax record.
- Invoicing clients abroad: Some international clients or platforms ask for a UK tax number when onboarding suppliers. For a sole trader, the UTR is usually the right number to provide on a W-8BEN-E or similar form.
- Opening a business bank account: UK banks collecting CRS self-certification data from business account holders will ask for a TIN. For a limited company, this is the company UTR.
- Applying for a mortgage or loan as self-employed: Mortgage lenders regularly ask for a UTR to verify self-employment income and cross-reference with HMRC records.
The current Income Tax rates that apply to your self-employment profits for the 2026 to 2027 tax year are set out below. These are the bands your UTR-linked Self Assessment return is calculated against:
| Band | Taxable Income (2026–27) | Tax Rate |
|---|---|---|
| Personal Allowance | Up to £12,570 | 0% |
| Basic Rate | £12,571 to £50,270 | 20% |
| Higher Rate | £50,271 to £125,140 | 40% |
| Additional Rate | Over £125,140 | 45% |
Source: GOV.UK — Income Tax rates and Personal Allowances (tax year 6 April 2026 to 5 April 2027)
The Personal Allowance of £12,570 is the same threshold that appears on your Self Assessment return as the tax-free portion of your profits. Your UTR is the reference that connects your annual return to those rates.
How Do You Get a UTR Number If You Do Not Have One?
If you are self-employed and have never registered for Self Assessment, you do not yet have a UTR. You need to register with HMRC before the 5 October deadline following the tax year in which you first had self-employment income.
Registration is done through HMRC’s online Government Gateway service. Once you register, HMRC sends a UTR by post to your registered address. This typically takes 10 to 21 working days. If you need your UTR urgently — for example, to complete a bank form or a contract — call HMRC on 0300 200 3310 and they can confirm the number by phone once your identity has been verified.
For a new limited company, HMRC automatically registers the company for Corporation Tax within a few weeks of Companies House confirming incorporation. The company UTR arrives by post at the company’s registered address, usually within four weeks of the company being set up.
If you are a director of a new limited company and are also paying yourself a salary, you will need two separate references: your personal UTR for your own Self Assessment (covering your salary and any other personal income) and the company UTR for the company’s Corporation Tax return. They are different numbers and serve different purposes.
FAQs About Tax Identification Number in the UK
Does everyone in the UK have a TIN?
Every UK resident has a National Insurance number, which functions as their personal TIN for most purposes. Not everyone has a UTR — you only get one when you register for Self Assessment or when a company you are associated with is registered for Corporation Tax. If you are purely a PAYE employee with no other income, your NI number is all you need as a UK TIN.
Is a UK VAT number a tax identification number?
A VAT Registration Number is a tax reference, but it is specific to VAT reporting and is not the same as a general TIN. When an international form asks for a UK TIN, providing a VAT number is generally not appropriate unless the form specifically relates to VAT or the institution confirms they will accept it. For most CRS and FATCA forms, the UTR or NI number is the correct number to provide.
Can I use my NI number and UTR interchangeably as a TIN?
No. Your NI number identifies you as an individual. Your UTR identifies your specific tax account — personal Self Assessment or company Corporation Tax. On a CRS self-certification form from a bank, an NI number is typically appropriate for an individual account. On a tax return or a form from a business counterpart asking for your tax reference, a UTR is what they want. Using the wrong one does not cause a tax problem, but it can slow down processing or trigger follow-up questions.
What do I do if a form says the UK does not issue TINs?
Some older or automated international forms flag the UK as a country that does not issue TINs, which can cause a ‘no TIN available’ scenario in their dropdown menus. In that case, most forms allow you to provide a reason code or a written explanation. Enter your NI number or UTR in the free text field and explain that the UK does not issue a single TIN but that you are providing the appropriate HMRC reference number in accordance with HMRC guidance IEIM902330.
Final Thoughts
The confusion around UK TINs exists because the UK simply does not use the term the way other countries do. There is no card, no certificate, and no single number called a Tax Identification Number. Instead, HMRC uses purpose-specific identifiers that each serve the TIN function in their own context: the NI number for individuals, the UTR for self-employed people and companies, the VAT number for VAT reporting, and the CRN in certain digital platform reporting regimes.
Once you know which number applies to your situation, the practical question of what to write on a form becomes straightforward. Employed individual? NI number. Sole trader or director? UTR. Limited company? Company UTR.
If you are running a limited company or working as a self-employed person and you are unsure how your various tax references connect to your filing obligations, the team at Micro Entity Accounts can review your position and make sure you are registered correctly with HMRC from the start.
Disclaimer: The content on MicroEntityAccounts is for informational purposes only and do not constitute tax or financial advice. We recommend consulting a certified tax professional or the HM Revenue and Customs Dept (HMRC) for accurate guidance. MicroEntityAccounts is not responsible for any decisions made based on the information provided.
