Guide to Tax Identification Numbers (TINs) in the UK

PHS Team

23 Jun, 2025

A Tax Identification Number (TIN) is a unique number used by tax authorities to identify individuals and businesses for tax purposes. While many countries issue one standard TIN, the UK does not have a single official tax identification number. 

Instead, HMRC uses different reference numbers such as the Unique Taxpayer Reference (UTR), National Insurance (NI) number, and VAT number, depending on the taxpayer's situation. These identifiers are essential for filing taxes, managing business accounts, and complying with international tax rules. 

Whether you're self-employed, employed, or running a business, understanding your UK TIN number is important to staying compliant. In this blog, we explain what a TIN means in the UK and how to find the right number for your needs.

What Is a Tax Identification Number (TIN)?

A Tax Identification Number (TIN) is a unique number used by tax authorities to identify individuals and businesses for tax purposes. In the UK, a TIN can refer to different numbers depending on the taxpayer’s status.

For individuals, the most common form of TIN is the National Insurance Number (NINO). For businesses, it may be the Unique Taxpayer Reference (UTR) issued by HMRC. Companies also use their Company Registration Number (CRN) or VAT registration number, depending on the context.

HMRC may request your TIN when you interact with them or if you have foreign tax obligations. While the UK does not issue a single number officially labelled "TIN," existing identifiers fulfil this role.

Does the UK Have a TIN?

No, the UK does not have just one TIN tax identification number. Instead, different numbers are used depending on the type of tax or who you are. HMRC uses these numbers when you:

• File a tax return
• Register a business
• Report income to another country

These numbers are also used in global tax forms like:

• CRS (Common Reporting Standard)
• FATCA (Foreign Account Tax Compliance Act)

Common UK Numbers Used as TIN Numbers

In the UK, there is no single official “Tax Identification Number” (TIN). However, HMRC uses different tax reference numbers depending on whether you are an individual or a company. These numbers serve the same purpose as a TIN and are accepted in the UK and abroad for tax identification. Below are the most common ones:

For Individuals

1. UTR (Unique Taxpayer Reference)

The UTR is a 10-digit number issued by HMRC when you register for Self Assessment. It’s used to identify you for income tax purposes. You’ll need it when filing tax returns or contacting HMRC about your tax affairs. It acts as your main tax identification number UK if you’re self-employed or earn untaxed income.

It includes:

• 10-digit number (e.g., 1234567890)
• Issued by HMRC upon Self Assessment registration
• Used for income tax and Self-Assessment
• Most commonly accepted as the UK equivalent of a TIN

2. NI Number (National Insurance Number)

A National Insurance number is used to track your National Insurance contributions and income from employment. Although it's mainly for social security, it may be accepted as a UK TIN number in international contexts.

It includes:

• Format: 2 letters + 6 numbers + 1 letter (e.g., AB123456C)
• Used for employment, benefits, and pensions
• Sometimes accepted on international tax forms
• Not issued by HMRC but still used in tax systems
   

For Companies

3. Company UTR (Unique Taxpayer Reference for Businesses)

When you set up a company in the UK, HMRC sends a Company UTR. This 10-digit number is used for Corporation Tax. It serves as the British tax identification number for businesses.

It Includes:

• A 10-digit number sent by HMRC after company registration
• Used for Corporation Tax returns and communication with HMRC
• Functions as the company’s TIN for UK tax purposes
• Not to be confused with the Companies House number

4. VAT Registration Number

If your business is VAT-registered, you’ll receive a VAT number from HMRC. It’s required for VAT invoices, returns, and reclaiming VAT on purchases. Many countries treat the VAT number as a valid TIN tax identification number UK for business transactions.

It Includes:

• Usually 9 digits, starts with “GB” (e.g., GB123456789)
• Used for VAT returns and sales invoices
• Often accepted as a TIN on international forms
• Issued when you register for VAT with HMRC

Where to Find Your Tax Identification Number

Here’s where you can look to find your tax numbers:

These are the main numbers that work as your tax identification number UK. Keep them stored safely, you’ll need them for tax returns, official forms, and sometimes for banking or working abroad.

When Will You Be Asked for a TIN?

You may need to give your UK TIN number in the following situations:

• Filing tax returns with HMRC
• Opening a bank account abroad
• Investing money overseas
• Filling in forms like W-8BEN
• Doing business across borders

In these cases, your UTR, NI number or VAT number will be used.

While the UK doesn’t issue one official Tax Identification Number (TIN), several tax reference numbers, like the UTR, National Insurance number, and VAT number, serve the same purpose. These identifiers help HMRC track tax records and are often used for international forms. If you're ever unsure, you can always contact HMRC or check your online tax account for help.

If you're self-employed or running a business and are unsure about your tax identification number (TIN) in the UK, PHS Associates is here to help. We can guide you in understanding which number applies to your situation, whether it's a UTR, National Insurance number, or VAT number. 

Our team will assist you in locating these numbers through HMRC documents or your online tax account and explain how to use them correctly for tax filing, business compliance, or international forms. Contact us by phone at 0208 8611685 or by email at info@phs-uk.co.uk  if you need accountants. Whether you're just starting your business or need help staying on top of your tax responsibilities, PHS Associates makes the process simple and stress-free. 

FAQ’s

What is the format of TIN in the UK?

The UK does not have a single TIN format; common equivalents include the 10-digit UTR, the NI number (e.g. AB123456C), and the VAT number (e.g. GB123456789).

How to verify TIN number?

In the UK, you can verify TIN equivalents like UTR, NI number, or VAT number through your HMRC account or official tax documents.

Who uses a TIN?

Individuals, businesses, and companies use a TIN for tax reporting, filing returns, and international financial compliance.