Tax Identification Number (TIN): A Beginner’s Guide to EU and Global Tax IDs

When you open a bank account abroad, take up a job in another country or set up a business, one of the first things you will be asked for is your tax identification number. Tax authorities, banks and employers all rely on these codes to know exactly who is paying tax on what — both at home and across borders.

In this guide, Eesti Firma, a licensed corporate services and accounting provider, explains in plain language what a TIN is, who issues it, where to find yours, how it differs from a VAT number and why so many institutions keep asking for it.

What Is a TIN?

A Tax Identification Number (TIN) is a unique code that the tax authority assigns to a taxpayer. It lets the state tell people and companies apart and make sure a tax return or a payment is matched to you — not to someone else with the same name. In some countries it is a separate, tax-only number. In many others it is simply your personal identification code or your company’s registration number doing double duty as a tax number.

Where to Find Your Tax ID

The European Commission and the OECD both publish examples of the taxpayer identification numbers used in EU member states and many other jurisdictions. These databases describe the format, structure and issuing authority of each national number. The Commission’s portal also includes an online module that checks whether the format of a tax number you have been given is valid.

Estonia is a special case: it is one of the countries that issue no separate tax-specific number. To find out which codes are used instead — and what to enter when a form asks for an Estonian TIN — see our guide on how the TIN works in Estonia.

Types of Tax Identification Numbers

Different taxpayers get different kinds of numbers. The names vary from country to country, but the main categories look like this:

• Personal identification code — the number an individual uses for taxes, government services and identification in general. For most people, this is simply “their” number.
• Registration code for legal entities — essentially the personal code of a company: assigned when the business is entered in the national register and used for taxes and official paperwork ever after.
• Individual Taxpayer Identification Number (ITIN) — a US number for foreigners who owe tax in the United States but cannot get a regular Social Security Number.
• Employer Identification Number (EIN) — a US number for businesses that hire staff, used mainly for payroll taxes.

The last two come from the American system, but the idea is universal: many countries issue extra special-purpose numbers on top of the basic personal and company codes. What matters in practice is simple — know which number applies to you and quote it correctly.

TIN vs VAT Number vs EORI: What’s the Difference?

A taxpayer usually holds more than one official number, and on forms they are easy to confuse. Three get mixed up all the time:

• TIN — identifies the taxpayer as such, for all taxes. It is assigned automatically or on registration and normally stays with you for life.
• VAT number — a separate number that exists only after a business registers for value added tax. It appears on invoices and is used for VAT purposes only; in the EU it starts with a two-letter country code and can be checked in VIES. A company can be fully operational and have no VAT number at all.
• EORI number — an EU customs identifier required for importing and exporting goods. It has nothing to do with income taxation.

The rule of thumb: the TIN answers the question “who is this taxpayer?”, while the other numbers answer “is this business registered for a specific activity?”. One more misconception worth clearing up: holding a TIN in a country does not by itself make you a tax resident there — the number identifies you, while residency is decided by entirely separate rules.

What a Taxpayer ID Is Used For

Whatever form it takes locally, the taxpayer ID serves the same purpose everywhere: reliably telling the authorities who is who. In practice this shows up in four main areas.

Tax Administration

Every return you file and every payment you make carries your number. That is how the tax authority knows whose return it is, checks that the sums add up and keeps your taxpayer record in order — without mixing you up with anyone else.

Banking and Financial Services

When you open a bank account or sign up with an investment platform, the form will almost always ask for your tax residency and your TIN. Banks must verify who their clients are — the Know Your Customer (KYC) checks — and follow anti-money laundering (AML) rules, and the TIN is a key part of that identification.

International Information Exchange

Countries routinely tell each other about bank accounts, income and assets that foreigners hold on their territory — within the EU under the administrative cooperation rules, and globally under the Common Reporting Standard (CRS) and the US FATCA regime. The tax ID is what lets the receiving country match the incoming data to the right person or company.

Employment and Payroll

Your employer uses your taxpayer number to withhold income tax from your salary, pay social contributions and file payroll reports. If the number on file is correct, your pay and your taxes are processed smoothly and end up in the right place.

EU Rules on Taxpayer Identification

Each EU country keeps its own laws and its own tax number format. On top of that, a few EU-level rules decide how these numbers are used and shared between countries. You do not need to know them in detail — but it helps to understand what they actually do.

Directive 2011/16/EU on Administrative Cooperation (DAC)

The Directive on Administrative Cooperation is the EU’s framework for tax authorities helping each other. In plain terms: member states share information about taxpayers — some of it automatically (for example, data on income and bank accounts), some on request — under fixed deadlines and strict data protection rules, including the GDPR. The directive has been expanded several times to cover financial accounts, cross-border tax schemes and company reporting. In every one of these exchanges, the taxpayer’s identification code is what links the data to a specific person.

Regulation (EU) No 904/2010 on Combating VAT Fraud

For value added tax, the key instrument is Regulation (EU) No 904/2010, which sets out how EU tax authorities work together on VAT and tackle VAT fraud. In practice it means:

• Information exchange — countries share data on cross-border trade, so VAT declarations can be checked against what actually happened.
• VIES — the VAT Information Exchange System lets anyone verify a counterparty’s VAT number online in seconds; businesses use it before invoicing partners in other EU countries.
• Fraud prevention — joint tools for spotting discrepancies and stopping schemes such as carousel fraud.
• Confidentiality — exchanged data may be used for tax purposes only, under strict data protection standards.

Tax ID Formats by Country

Tax identification systems have grown out of each country’s own administrative history, so the numbers differ in length, structure and even in whether a dedicated tax number exists at all. The table below shows what tax ID numbers look like for individuals and companies in a selection of jurisdictions.

Despite all the differences in format, the goal is the same everywhere: a unique, stable identifier that lets tax administrations process returns efficiently, keep records accurate and cooperate across borders.

Key Takeaways

A Tax Identification Number is the code that connects a taxpayer — an individual, a company or a foreign person — to their tax obligations. Formats vary widely between countries, and in many places the role of the tax ID is played by an existing identifier such as a personal code, a social security number or a business registry code. Whatever the local flavour, it is the number that banks, employers and tax authorities will ask for first.

Quoting the correct taxpayer number keeps filings accurate, speeds up KYC checks and prevents problems with international information exchange under CRS, FATCA and the EU cooperation rules. For anyone doing business across borders — for example, founders who establish a company in Estonia while living elsewhere — understanding which numbers identify them in each jurisdiction is a basic part of staying compliant.

If you are unsure which tax ID number applies in your situation, or you need help with tax registrations, reporting or official documents in different jurisdictions, the Eesti Firma team is happy to assist.

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