What is Tax Identification Number (TIN)? Ultimate Guide: 2026

If you've ever filled out a tax form, opened a bank account, or started a business, you've encountered Tax Identification Numbers. But most people don't realize there are actually five different types of these numbers, and using the wrong one can delay your refund by months.

For businesses, the confusion multiplies. You might need an EIN for federal taxes, a state tax ID for sales tax, and sometimes a separate number for payroll taxes. New business owners often discover they've been using their SSN when they should have applied for an EIN, or they have an EIN but forgot to register for state tax identification. International businesses face another layer, determining whether they need an ITIN, EIN, or both for their U.S. operations.

This guide started as a reference document we created after researching TIN requirements for various business situations. After helping numerous entrepreneurs and tax professionals navigate these requirements, we noticed everyone had the same questions. The IRS website has all this information somewhere, but it's scattered across dozens of publications.

We've organized everything you actually need to know about TINs in one place.

What Is a Tax Identification Number (TIN)?

A Tax Identification Number (TIN) is a government-issued identifier used to track the tax obligations of individuals and businesses. In IRS’s own words,

“A Taxpayer Identification Number (TIN) is an identification number used by the Internal Revenue Service (IRS) in the administration of tax laws.”

The IRS (In the US) issues different types of TINs.

• SSN (Social Security Number), for U.S. individuals
• ITIN (Individual Taxpayer Identification Number), for non-eligible SSN filers
• EIN (Employer Identification Number), for businesses and entities
• ATIN (Adoption Taxpayer Identification Number), for children in adoption process
• PTIN (Preparer Tax Identification Number), for paid tax preparers

Each has its own pattern, but they all serve the same purpose: linking tax activity to the right person or business.

We will learn about it all more deeply in the next section.

Other countries handle this differently. Some use one national number for taxes and identification, while others assign separate codes for individuals, businesses, and foreign nationals. The name, length, and structure vary widely from place to place.

The idea is the same everywhere though: the system needs a clean way to know who’s who when money and taxes get involved.

Common types of TINs

There are usually five main types of TINs any country can have: one for individuals, one for businesses, one for people who don’t fit the standard system, one for temporary situations, and one for professionals involved in tax work.

“Your tax id number in the US is your SSN unless you’re setting up your stream info with a business/LLC that you own in which case it is referred to as your tax ID number” —Tyl3rt on Reddit

To keep things simple, we’ll look at the US versions first since they cover all five categories. After that, we’ll list the country-by-country counterparts so you can see how other places map to the same idea.

Here’s the list of TIN counterparts in other countries:

• United Kingdom: NINO, UTR
• Canada: SIN, BN
• Australia: TFN, ABN
• India: PAN, TAN
• Brazil: CPF, CNPJ
• Germany: Steuer-ID, Wirtschafts-Identifikationsnummer
• France: Numéro Fiscal, SIREN/SIRET
• Spain: NIF, NIE, CIF
• Italy: Codice Fiscale, Partita IVA
• Mexico: RFC
• Netherlands: BSN, RSIN
• Sweden: Personnummer
• Finland: Personal Identity Code
• South Africa: Income Tax Reference Number
• UAE: TRN
• Singapore: NRIC/FIN, UEN
• Kenya: KRA PIN
• Nigeria: TIN (JTB/FIRS)
• New Zealand: IRD Number
• China: Taxpayer Identification Number tied to Citizen ID or Unified Social Credit Code
• Japan: MyNumber
• Ireland: PPSN, TRN

With core types explained, let’s now explore the use cases of TIN.

TIN use cases: How does TIN work?

A TIN acts as a reference code a tax authority uses to track income, filings, and financial activity. Once assigned, it stays tied to the person or entity and shows up whenever there’s a need to match financial records with tax records. How it works can shift slightly depending on whether it’s an individual, a company, or someone operating across borders.

How to apply for TIN?

Applicants need to start by applying with the official authority, provide basic documents, submit the application, and wait for the system to generate your number.

Step #1: Go to the official portal or tax authority

Every application begins with the country’s tax department or revenue authority. For the United States, this means the IRS (Internal Revenue Service). They handle SSNs via the SSA, EINs through IRS.gov, and ITIN applications through designated IRS processes.

If you reside outside the USA, you’ll find their official portals listed in this table.

Step #2: Gather the required documents

You only need two sets of documents for most TIN applications. One set proves who you are. The other proves where you live or where the business operates.

Step #3: Submit the application online or through an approved channel

Some countries let you apply fully online. Others use a mix of online forms, in-person visits, or authorized intermediaries such as accountants or registration agents. Business IDs often require extra verification because of compliance rules, while individual applications tend to move faster.

Businesses that onboard multiple applicants or vendors often automate this step with verification platforms like Signzy, where identity documents, formats, and TIN-linked data can be validated before submission to avoid rejection or delays.

Step #4: Wait for confirmation and activation

After submission, the authority reviews your documents and issues the number once everything checks out. Processing times vary. Some countries generate a TIN instantly. Others take a few days or weeks.

Also, remember getting ITIN can be a bit different from what we discussed above since multiple dynamics come into play. Sharing the solution, one user on Reddit commented,

“You need to file Form W-7 to get an ITIN. In order for them to issue an ITIN, you need income taxable in the US, and file the application with a tax return. They generally won't issue an ITIN before you actually have income. There are a few exceptions to this (so that you can file without a tax return) on the Form W-7 instructions. You might fall under one of these exceptions, you might not.”

Lastly, once you receive your TIN, the number becomes the anchor for all future tax filings, financial activity, and regulatory records in that jurisdiction.

Can you have more than one TIN? What happens when you move countries?

Holding more than one TIN isn’t unusual at all. It’s a normal part of living or working across borders. People often end up with more than one TIN when they interact with more than one tax system. A person living in the US might get an SSN. If they move to Canada, they receive a SIN. Both numbers stay active in their respective countries. Neither replaces the other. Each belongs to a different system with its own rules.

Moving countries adds layers. The old number doesn’t vanish. It stays tied to past filings. The new country issues a new identifier for new obligations. Some people also keep tax responsibilities in their old country, especially if they own property, investments, or businesses there. This creates a mix of numbers, each serving a different purpose.

Compliance Side of TIN

A TIN sits at the center of almost everything that touches compliance. Compliance teams lean on it because it simplifies the three main bottlenecks of verification.

1. A number is easier to validate than stacks of documents.
2. A number is easier to track through systems.
3. A number can be checked, flagged, blocked, cleared, or logged in ways that keep everything clean.

When you look at the world of taxes, banking, anti-fraud checks, and cross-border reporting, the TIN keeps the whole system from collapsing under confusion.

TIN and ID Verification

Verification always starts with one question. Who is this person or entity. A TIN gives the answer in a way the system can understand. Banks take the number and match it with government data or internal records. Employers link it with payroll. Tax authorities check it before they accept any filing. Payment processors load it into their risk engines to work out what kind of activity looks normal.

The process feels simple on the outside. You provide the number. The system checks if it exists. It compares details like your name, address, and date of birth. Anything that doesn’t fit raises a flag. A person using an incorrect or mismatched number gets slowed down or stopped completely. That’s the point of verification. Keep the right people in the flow. Keep everyone else paused until things make sense.

🎯 Signzy Advantage: Signzy ties TIN validation to document checks, OCR accuracy, biometric match and fraud-detection signals, so the identity tied to a TIN is confirmed, and not just accepted.

TIN and KYC

KYC is a gatekeeper. Institutions need to figure out if the person sitting in front of them is real. A TIN helps confirm that the identity matches what’s in official records. When someone opens a bank account or investment account, the TIN lines up with the documents they hand over. If it doesn’t line up, the application stalls.

KYC systems run the TIN through internal and external checks. Sometimes it’s a direct lookup through a government system. Other times the check runs through providers like Signzy, Trulioo, or GBG for formatting intelligence, identity matching, and risk signals. The check isn’t only about validity. It’s about consistency. If the TIN appears in past filings tied to different names or addresses, the profile feels off and gets flagged.

This way, TIN matching reduces fake identities, duplicate accounts, and recycled credentials. Without a functioning TIN check, verification becomes guesswork, and compliance teams end up spending hours on manual follow-ups.

🎯 Signzy Advantage: TIN checks run alongside identity, sanctions, PEP screening and fraud markers in one workflow, reducing manual reviews and accelerating approvals without lowering controls.

TIN and KYB

For businesses, KYB works the same way but with more steps. A company hands over its TIN so banks and payment providers can confirm that the entity exists in official registers. They check the company’s formation records. They match the number with ownership details. They look at who controls the entity.

A company’s TIN also helps track obligations the business hasn’t met. Unfiled returns. Unpaid taxes. Suspicious patterns in invoices. Regulators rely on it during audits because it shows what the business reported and how that compares to what’s happening in the real world. KYB teams depend on this trail to decide if a company should be trusted.

🎯 Signzy Advantage: Signzy connects TIN validation with Secretary-of-State records, business registries, ownership data and compliance checks, giving a single accurate source of truth for entity onboarding.

TIN and AML

AML checks deal with patterns. Money that moves too fast. Money that moves without context. Money that lands in a place it shouldn’t. A TIN gives investigators a fixed point to start from. The number ties back to a person or company. Once they know who sits behind the activity, they can figure out if the movement makes sense.

TIN checks at the AML stage also help detect laundering methods like mule accounts, identity swapping, duplicate identities spread across institutions, and false residency declarations. Vendors such as Signzy, LexisNexis, and GBG help enrich AML systems with validation, watchlist cross-referencing, and fraud patterns tied to specific TINs.

🎯 Signzy Advantage: TIN results feed directly into AML scoring and monitoring rules, helping detect synthetic identities, mule accounts and mismatched identity trails earlier in the risk pipeline.

TIN and FATCA / CRS

Cross-border tax rules depend heavily on TINs. Banks collect the number from customers with foreign tax obligations. They file that number with foreign tax authorities. The TIN becomes the way countries share information with each other without confusing one person for another.

FATCA and CRS reports rely on correct TINs. If the number is missing or wrong, the account may get blocked or classified as non-compliant. For global workers, digital nomads, or investors handling money in multiple countries, this number is the only thing that keeps their filings from getting tangled up across borders.

🎯 Signzy Advantage: Signzy supports multi-country document verification, identity matching, and TIN checks in workflows built for FATCA and CRS submissions, reducing remediation work and preventing classification issues.

TIN and transaction monitoring

Monitoring systems watch every transfer. They don’t know who people are unless the TIN fills the gap. The number attaches to each party in a transaction, which helps the system spot patterns. Suspicious amounts. Unexpected spikes. Transfers that don’t line up with known income levels.

When the TIN matches trusted registry data, the system processes the transaction normally. When it doesn’t, the transfer may be paused, flagged, or pushed to manual review. Providers like Signzy help enrich monitoring systems with structured validation so the matching logic isn’t only format-driven but grounded in live registry and compliance data.

Good TIN hygiene reduces false positives and accelerates clearing legitimate transactions. Bad or missing TIN data forces monitoring teams into detective mode.

🎯 Signzy Advantage: Signzy feeds validated TIN data directly into monitoring engines, which means cleaner baselines, fewer flagged customers, and faster decision cycles, especially for payouts, recurring payments, and vendor disbursements.

“Before Signzy, nearly half of our international applicants stalled because their tax IDs wouldn’t validate cleanly. After implementing automated checks, the approval rate for foreign users improved by about 28%, and support tickets related to TIN issues fell sharply.” —Head of Vendor Operations (Global marketplace processing ~50k monthly applications)

How to check or verify a TIN?

Verifying a TIN looks simple from the outside, but once you get into the details, you realize every country treats the process a little differently. Some give you a direct way to validate the number. Others lock their systems down and expect you to rely on formatting rules, internal checks, or the documents the person brings.

Usually, banks, employers, and compliance teams usually have quicker access to confirmation tools, but the basic idea is the same no matter who’s doing the check. You want to make sure the number is real, active, and tied to the person or business claiming it.

Step #1: Start with the government source or the third party verification tool

If the country offers a verification tool, that’s where you begin. It’s the only place that ties directly into the tax authority’s internal records. Spain has one. Brazil has one. The US only offers public verification for EINs, not SSNs or ITINs. Some countries allow partial matches. Others only confirm validity in the background without showing any personal data.

Most people expect a universal global tool. There isn’t one. Countries protect their databases, so you start with whatever the local authority provides.

While this process works well for small volume requirements, this can break or consume a lot of resources when you need to verify TINs at scale. Solutions exist and we are going to discuss them after step 5.

Step #2: Check the format and structure against known rules

Every TIN has a pattern. Length. Character mix. Sometimes check digits. Sometimes a country code is hidden inside the number. A wrong digit in the wrong spot instantly breaks the pattern. You can rule out a lot of problems with a two-second glance if you know the format.

This isn’t perfect, but it catches most of the obvious mistakes before you go deeper.

Step #3: Match the TIN with the person or business in front of you

A valid number doesn’t mean it belongs to the person using it. That’s where the identity match comes in. Banks compare the TIN with legal documents. Employers check it against payroll history. Tax offices run the number through internal records to see if the name and address line up.

If anything feels off, the system slows or stops the process to protect both sides. It’s one of the quiet ways the system catches impersonation and accidental mix-ups before they spread.

Step #4: Confirm the activity status

TINs can go inactive. Businesses close. People move. Entities merge. Some numbers fall out of use after years of no filings. Others get deactivated because of unresolved issues.

You don’t always get a public status check, but government systems can detect it the moment a filing or payment hits. For individuals, inactivity usually shows up when a return gets kicked back. For companies, banks pick up on it during KYB checks.

Step #5: Review supporting documents if the tin comes from another country

Foreign TINs follow their own rules. A bank in the US can’t directly verify a French NIF or a Brazilian CPF in real time. When a foreign number shows up, supporting documents fill that gap.

Passports. National IDs. Business registration papers. Residency permits. Anything that shows the person or business actually exists in that jurisdiction. It’s slower, but cross-border checks always take a bit more time.

Now, the rest of this section is for businesses who need to conduct TIN verification at scale.

At scale, tools like Signzy automate formatting rules, registry checks, identity validation, and document matching so teams don’t manually search government portals or compare mismatched records.

“TIN checks used to drag out onboarding for days. After switching to Signzy, our average verification time dropped by roughly 40 percent and most cases clear without any manual touch. The difference is noticeable across the team.” —Chief Compliance Officer (Payroll and benefits platform, 500+ employees)

They’re most useful when you need to check TINs in bulk. We’ll explore these solution providers later in the guide since they fill in many of the gaps.

TIN verification importance, at a glance

Since we discussed how to verify TIN, it would be better to understand the WHY behind it, In short, verifying a TIN protects the entire workflow. It stops bad records from entering the system and keeps financial, tax, and compliance processes from breaking later.

Below are some reasons businesses shouldn’t overlook TIN verification:

💡 It stops payments from going to the wrong party: When a vendor’s TIN doesn’t match their legal name or registration, the payment system can’t confirm the entity. This prevents invoices from being paid to businesses that don’t legally exist or to accounts set up under misleading identities.

💡 It prevents supplier and partner onboarding failures: KYB checks rely heavily on a clean TIN match. If the number doesn’t align with the company registry, ownership records, or the entity’s status, the onboarding pipeline halts. This avoids adding unstable or unverified partners into long-term workflows.

💡 It keeps statutory reporting accurate: Payroll filings, withholding summaries, VAT submissions, and contractor reports all rely on correct TIN data. A single incorrect number can break automated filings, create mismatches in government records, or trigger penalties for incorrect submissions.

💡 It reduces exposure to fraudulent entities: Fake businesses often use invalid or recycled TINs. Verifying the number helps detect shell companies, duplicate identities, and entities created for invoice fraud, saving the business from chargebacks, disputes, or lost funds.

💡 It maintains compliance across borders: Cross-border payments and multi-country operations depend on confirmed TINs. FATCA, CRS, and VAT systems treat unverified tax IDs as compliance gaps, which can lead to withheld transfers, delayed settlements, or flagged accounts.

💡 It minimizes operational slowdowns: When a TIN fails later in the workflow, everything attached to it slows down, payments, vendor contracts, KYC/KYB checks, and even simple account updates. Verifying early prevents these cascaded delays.

As you can see, for any business dealing with contractors, employees, vendors, or partners, a quick TIN check removes uncertainty and keeps financial and compliance processes steady from the start.

Best third party TIN verification solutions

Third-party TIN verification providers plug into official business registers, public tax records, national ID datasets, VAT systems, watchlists, sanction databases, and a long list of compliance sources that aren’t always easy to work with directly.

This way, instead of searching ten different portals, decoding formats you’ve never seen before, and hunting through documents that don’t share a language, you type the number in one place. The engine behind the scenes handles the rest. It validates the format, checks the number against external records, confirms business registration status where possible, and flags activity that doesn’t feel right.

It’s just the result of a lot of integrations stitched together in a way that feels invisible when it works.

There are several strong identity and KYB vendors, but only a few treat TIN verification as a first-class problem. Here is how they stack up when TIN accuracy, speed, and workflow fit really matter.

Signzy: Best TIN verification solution overall

Signzy was built to handle identity and compliance checks without turning the whole process into a maze. The platform pulls data from tax authorities, business registers, national ID systems, and regulated data partners, then layers TIN validation on top of that foundation. The goal has always been the same. Keep the workflow clean. Cut down on the back-and-forth. Remove the awkward manual steps that slow everything down.

Accuracy matters, but so does speed, which is why Signzy is built to handle high-volume verifications. Signzy can support multiple regions, multiple formats, and mixed-use cases where a business might need to check personal TINs, business TINs, or foreign identifiers in the same pipeline.

On top of everything, you can always add more modules as and when needed. AML screening, biometric checks, liveness authentication are some of the examples.

🔒 User reviews

“We handle thousands of EIN and SSN verifications every month, and mismatches used to be a constant blocker. With Signzy plugged into our workflow, mismatch rates dropped by about 30% and the back-and-forth with vendors reduced to almost nothing” — Chief Risk Officer (Fintech, 1000+ employees)

"We went from 3-day onboarding cycles to same-day approvals, and our TIN mismatch rate dropped from 12% to under 2%. Signzy just works." — PMM (BFSI, 200+ employees)

Trulioo

Trulioo covers a wide sweep of countries and pairs identity data with business verification records. It isn’t limited to TIN checks. It bundles in document verification, watchlist screening, and business registry matching. The strength here is reach. If you’re dealing with customers across borders, Trulioo gives you one place to run the checks without switching between regional tools.

LexisNexis Risk Solutions

This one targets teams that deal with higher-risk profiles or need deeper due-diligence layers. It connects with corporate registries, tax identifiers, sanctions lists, and public data sources. The system focuses more on risk and monitoring than simple format checks. Good fit for banks and financial institutions that need a heavy background check wrapped around TIN verification.

GBG

GBG offers identity and business verification for multiple countries. It pulls data from official registers, electoral rolls in some regions, and commercial datasets that track business activity. Their TIN checks are usually bundled inside broader compliance flows, which makes them helpful for companies that prefer everything under one dashboard.

Buyers can refer to this comparison snapshot of best KYC solutions for quick assessment

What happens when a TIN is missing, incorrect, or invalid?

A missing or wrong TIN tends to break things fast. Systems that rely on the number don’t know who they’re dealing with. That leads to delays, blocked applications, and rejected filings. It can also cause problems in payroll or banking because those systems need a clean match before they move forward.

“There are specific SSNs that are publicly known to be invalid due to historical misuse,” shared Aggressive-Dealer426 on Reddit. “A well-known example is 078-05-1120, which became widely circulated in 1938 when a wallet manufacturer used it as a sample SSN on display cards inserted into wallets sold across the U.S…As a result, it was used fraudulently thousands of times and has since been invalidated by the SSA.”

For individuals, an incorrect TIN creates issues during tax season. Returns bounce back. Refunds stall. Employers may flag the mismatch. For companies, it becomes even more visible. Payments freeze. Vendor records don’t update. Compliance checks fail. Everything slows down until the number is corrected.

The fix usually involves updating details in the right place. You correct the typo. You supply the right documents. You give the tax authority what they need. Once the system sees a valid number tied to the right profile, everything starts moving again.

What if a TIN doesn’t verify or returns no record?

A TIN that fails verification doesn’t always signal a major issue, but it does mean something doesn’t line up.

That’s the end of the guide. Thanks for staying with it. And if you want a system that can take TIN verification off your plate and run it smoothly at high volume, you can grab a no-pressure demo with Signzy here.