Tax Identification Number by Country: Which One to Give

A tax identification number is the number a country uses to identify a taxpayer.

For a company, most countries issue nothing with that name: "TIN" is a box on a form, and each country fills it differently.

The short answer

Three things to hold on to:

• Singapore, Estonia and Hong Kong reuse a registration number.
• Ireland, the United Kingdom and the United States issue a separate tax number.
• The form in front of you decides as much as the country does.

What a tax identification number is

HMRC's manual defines a TIN as a unique number "issued by a jurisdiction for identifying individuals and entities for tax purposes". Nothing in that definition requires the country to call it a TIN.

So a TIN is a function. Forms routinely confuse it with two neighbors:

In some countries one number does two of these jobs. That is the whole difficulty:

• In Singapore and Estonia, the registration number is the TIN.
• In Ireland and the United States, the registration number is never the TIN.
• In no country covered here is the VAT number the TIN.

A registration number, reused

Nothing to request from the tax authority.

• Singapore: the UEN
• Estonia: the registry code
• Hong Kong: first 8 digits of the BR number

A separate tax number

Issued by the tax authority, after its own step.

• Ireland: the TRN, from Revenue
• United Kingdom: the company UTR, from HMRC
• United States: the EIN, from the IRS

In none of the six is the VAT number the TIN.

A tax identification number is a role, not a document. Find out which number plays that role in the company's country of tax residence, then check which form is asking.

Which number each form wants

The same company gives different numbers to different forms. Four situations cover most requests:

1. A bank's CRS self-certification. It asks for the TIN and the country of tax residence together.
2. A US Form W-8. It asks a foreign payee for the tax number of its own country.
3. An invoice. It carries the VAT number, where the company has one.
4. A tax return. It carries the number the tax authority uses for the company.

	CRS form or W-8	Invoice	Tax return
Singapore	UEN	UEN	UEN
Hong Kong	First 8 digits of the BR number	BR number	BR number
Estonia	Registry code	VAT number, if registered	Registry code
Ireland	TRN	VAT number, if registered	TRN
United Kingdom	Company UTR	VAT number, if registered	Company UTR
United States	EIN	EIN, if the customer requires it	EIN

Green: a registration number doing the tax job. Amber: a number issued separately.

Two notes on the US forms:

• The entity version of Form W-8 asks for the tax number issued by the company's country of residence. A US company does not file it; it gives its EIN on a Form W-9.
• The individual version, Form W-8BEN, puts a US number (SSN or ITIN) on line 5 and the foreign number on line 6a.

Singapore: the UEN

Singapore issues TINs to entities automatically, and the number is the Unique Entity Number. The OECD sheet lists three formats:

In the company format, YYYY is a year and C is a check letter. There is nothing to request from the tax authority.

• A director's NRIC or FIN identifies the director, not the company.
• Where no NRIC, FIN or UEN exists, IRAS can assign its own tax reference number.

The individual cases and the edge cases are in the Singapore tax identification number, NRIC, FIN or UEN.

Hong Kong: the BR number

The OECD sheet is blunt: Hong Kong "does not issue TIN for communicating with taxpayers". Two existing numbers stand in.

• Individuals give their Hong Kong identity card number.
• Entities give the Business Registration number: the 8 digits at the front of the certificate number.

On the certificate, the number sits in the middle, under "Certificate No.". Since December 27, 2023, a newly incorporated company carries that number alone.

One number must not be used. The "TIN" a person may set for an eTAX account only opens the online account. A free online search returns a BR number from the full business name and its address district.

Read the Hong Kong TIN and the number that only looks like one before you fill in the form.

Estonia: the registry code

Estonia is the simplest case. Every legal person receives a unique registration code, and the OECD sheet calls it the "TIN for legal persons".

• It has 8 digits and no prefix.
• It begins with 1 for companies.
• It is assigned automatically at registration.
• It never changes.

Two numbers get mistaken for it:

• The VAT number. EE plus 9 digits, a different number, and only for VAT-registered companies.
• The personal identification code. 11 digits, and it belongs to a person, such as the e-resident founder.

The OECD sheet lists no online tool that validates the code as a TIN. The register itself is covered in how to read and verify an Estonian registry code.

Ireland: the Tax Reference Number

An Irish company's TIN is the Tax Reference Number. Revenue issues it when the company registers for tax, not at incorporation.

Two neighbors cause the errors:

• The CRO number is the public registration number, numeric, and not a tax number.
• The VAT number has the same shape as the TRN behind an IE prefix. Treat that as a resemblance of format, not as a rule.

We have no dedicated TRN guide yet. The closest is the Irish VAT number format and how to verify it.

United Kingdom: no single TIN

The United Kingdom issues no number called a TIN. Several numbers stand in for one, and for a company the answer depends on the regime.

• CRS, FATCA or W-8 form, foreign bank onboarding: the company's Unique Taxpayer Reference, 10 digits, from HMRC.
• Reporting by a digital platform operator: normally the company registration number, 8 characters, from Companies House.
• Any form: never the VAT number.

The practical rule is to read the guidance attached to the form. If it gives no steer, the UTR is the number HMRC issued for tax.

Two guides take it from there:

1. which UK number to give as a TIN, profile by profile
2. the difference between a company UTR and a personal UTR

United States: the EIN

The United States uses three taxpayer identification numbers. Only one belongs to a company.

For a company, the answer is the EIN.

• The IRS issues it on Form SS-4.
• International applicants can call (267) 941-1099, which is not toll-free.
• The state that formed the company does not change the federal number.

The state file number is a registration number, not a tax number. An ITIN belongs to the owner, never to the LLC. Both mix-ups are untangled in the Delaware file number and the EIN.

When there is no TIN to give

Sometimes the honest answer is that no number exists. Three situations produce it:

1. The jurisdiction issues none. Hong Kong gives an equivalent instead, and the form accepts it.
2. The company is not registered for tax yet. An Irish TRN and a US EIN both arrive after a separate step.
3. You are not a taxpayer there. Owning a company in a country does not make you personally tax resident in it.

What to do on the form:

• Give the number of the country where you or the company are tax resident.
• Use the reason field that CRS self-certifications provide when no TIN is available.
• On Form W-8BEN, line 6b is a checkbox for a foreign number that is not legally required.

What not to do:

• Do not invent a well-formed number.
• Do not substitute a passport number or a VAT number.
• Do not give a personal number in the entity section.

This page covers six jurisdictions only. For any other country, the OECD publishes an information sheet on its tax identification numbers.

The summary