Verifying tax ID numbers is critical for SaaS and AI companies with global customers. Whether you're billing EU clients or selling in Canada, providing a valid TIN often means the difference between charging tax—or facing penalties later. Invalid or missing tax IDs can lead to denied VAT recovery, audit risk, or retroactive tax bills that can seriously impact your bottom line.
Global tax compliance isn't just a "big enterprise" problem anymore. As digital reporting requirements tighten and cross-border enforcement accelerates, even mid-market companies need to validate tax IDs in real time.
Tax authorities are getting smarter about tracking transactions, and they're not hesitating to come after businesses that didn't properly verify their customers' tax status. For fast-growing companies selling internationally, compliance at scale starts with getting this fundamental step right from day one.
Can I Verify a Tax ID Number?
Yes, but the process varies depending on the type of tax identification number (TIN).
In the US, Employer Identification Numbers (EINs), are nine-digit numbers assigned to businesses by the Internal Revenue Service (IRS). They are used for identification of a business entity, hiring employees, registering for sales tax, and filing income taxes.
What are US TINs, SSNs, ITINs, and EINs?
This differs from the Social Security Number (SSN) and Individual Taxpayer ID Number (ITIN). Social security numbers are 9-digit numbers used by the US federal government to track earnings and administer social programs like Social Security benefits and disability payments. ITINs are similar, except they are issued by the US federal government to individuals who require an identification number but don’t qualify for an SSN.
While those three items are all issued by the US government, the term Taxpayer Identification Number (TIN) is a more blanket term that can be used to talk about any tax ID number, such as a sales tax registration number.
Why Verifying Tax IDs Matters
Beyond basic compliance, proper tax ID validation helps prevent fraud, ensures you can claim legitimate VAT or GST recovery where applicable, and protects you from penalties when tax authorities audit your customer records. For SaaS companies processing hundreds or thousands of transactions across multiple jurisdictions, getting this right is essential for maintaining clean books and avoiding costly compliance issues down the road.
Stay Compliant with Digital Reporting Rules
Governments expect businesses to use digital tools to verify tax IDs when doing business cross-border.
This is especially crucial when it comes to charging indirect taxes like VAT or GST. In many jurisdictions, you can avoid charging these indirect taxes to customers as long as that customer can prove they are a valid business. But that means you need to verify any TIN’s provided by your customer to ensure you’re taxing them correctly.
If caught not charging VAT or GST to a customer during an audit, your business could be on the hook to both pay the uncollected tax out of pocket, but to also cough up interest and penalties, too.
Prevent Fraud and Mistakes
Not all invalid tax treatment is due to a mistake. Some businesses deliberately provide incorrect TIN’s in order to avoid paying taxes. Unfortunately, that leaves your business paying the taxes in the event of an audit. And worse, when a bad actor is identified, vendors who do business with them are often also audited. Doing business with one fraudulent company, no matter how unintentional, can leave you in a world of tax compliance hurt.
Accidents also happen. Companies might make a typo on their federal tax identification number, or unthinkingly give you expired information. Verifying tax IDs helps alleviate these preventable mistakes.
Reclaim Input VAT or GST
Properly validating tax IDs is also crucial for tax recovery when you’ve paid VAT. For example, your business is charged VAT on a purchase you should not have had to pay for. In this case, you’re allowed to reclaim that input VAT as a VAT refund. However, taxing authorities scrutinize these claims closely–after all, they don’t want to give up any revenue they think they’re entitled to. Failing to provide proper tax ID information can cause your claim to be denied and you to lose out on that erroneously paid VAT. In the worst case scenario, this can even trigger an audit.
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How to Verify U.S. Tax ID Numbers
You may be required to verify the US tax ID number of a business or an individual.
How to Verify a Company’s EIN (Employer Identification Number)
EINs, i.e. business tax numbers, are 9-digit numbers issued to employers. Employers can get an EIN by filling out the IRS's EIN application (form SS-4). They’re used for activities like business registration and paying taxes.
Top solutions for EIN number verification include:
- IRS TIN Matching Program – This is the IRS’s TIN matching system. Registration at the IRS website required before use, and it's only available to authorized users. In this system, verifying a handful of TINs is a short process, but verifying a batch could take hours or days.
- IRS Business Line - You can call 800-829-4933 for EIN lookup. The number operates Monday-Friday, 7am to 7pm ET.
- EIN Verification/Confirmation Letter - The IRS’s Form 147C Letter. Third parties can fill out this form to request EIN confirmation. You must request this form by calling the IRS Business Line, above. Businesses should also have a copy of this letter, which you can request, though it is best practice to verify the information separately.
- SEC EDGAR System - If a business has filed with the Securities & Exchange Commission (SEC) (i.e. publicly traded companies), then you can view their filings, which include EINs, here.
- State business directories – Each US state's Secretary of State Division will have a version of “corporation search” where you can verify that a corporation is active.
- Third party lookup tools – Some third-party lookup tools promise to verify EINs automatically.
How to Verify an SSN (Social Security Number)
Businesses generally need to verify a social security number for an employee or contractor.
Verify through the Social Security Number Verification Services (SSNVS).
How to Verify an ITIN (Individual Taxpayer Identification Number)
US non-residents who aren’t eligible for an SSN but need a federal tax ID number are issued an ITIN.
You can check the status of an ITIN:
- By phone – You can check ITINs with the IRS at 1-800-829-1040 or 1-800-908-9982
- Online – The IRS’s TIN Matching Tool allows you to check an individual's ITIN. Registration is required.
How to Verify International Tax ID Numbers
It’s often simpler to verify VAT and GST numbers than TINs, because businesses need to verify indirect tax IDs often in order to perpetuate the flow of commerce.
How to Verify EU VAT Numbers
The EU’s 27 member states all have a unique VAT number format, generally starting with a country code. For example, Austria uses the letters ATU followed by 8 digits (i.e. ATU12345678). Number formats vary. In the Netherlands, the VAT number starts with NL and the 10th character is always a “B.”
The primary way to verify an EU VAT number is through the EU-wide VIES Validation System.
However, for increased reliability, you may want to try member state’s individual sites. For example, here’s how to validate a VAT number in Germany through the BZSt.
How to Verify UK VAT Numbers
UK VAT numbers use the prefix GB and then 9 character (i.e. GB123456789).
Verify UK VAT numbers at the HMRC website.
How to Verify Canadian Business Numbers
The Canadian Business Number (BN) consists of a 9-digit number, which is a federal identifier that combines with two-letter program codes and four-digit reference numbers to create 15-character account numbers. Provinces that also require tax registration have their own formats.
Federal BN’s are verified through the Canada Revenue Agency’s (CRA) online tool.
Provincial registration is verified at the various provinces.
How to Verify Australia GST Numbers
The Australian Business Number (ABN) is an 11-digit number that includes the GST registration number for easier verification.
Verify Australian business numbers at the ABN Lookup.
How to Verify VAT/GST IDs in Other Countries
How to Verify Tax IDs at Scale
Manual Methods (When Volumes is Low)
If you only have to verify a handful of tax ID numbers, then public tools like the IRS TIN Match, VIES for EU VAT, or the SSNVS for social security numbers should do the job.
However, if you’re verifying more than a handful for numbers, entering them manually can be tedious and time-consuming. These solutions usually also have daily volume limitations.
Some systems allow for bulk upload of multiple numbers, but this process can take hours or days to complete, making them difficult to build into your business processes.
Tax ID Verification Tools
Online third-party options like Fonoa and Tax ID Pro will allow you to verify tax ID numbers in real time, all in one place while automating the process, too. However, these solutions charge a monthly or annual fee as well as on a per API call basis. Additionally, they are yet another tool that needs to be integrated with your billing or accounting systems in order to automate TIN lookup.
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How Sphere Handles VAT Verification Automatically
Verifying TINs too time-consuming and tedious to handle? Sphere has you covered.
Sphere's APIs validate TINs globally, preventing you from having to manually type in numbers one by one, or create batches that can take hours or days to process. Instead of juggling different validation systems like VIES for EU customers, HMRC for UK clients, CRA tools for Canadian businesses, Sphere's unified platform automatically routes validation requests to the appropriate authorities and handles all the technical complexity behind the scenes.
Better yet, Sphere allows you to build in workflows to take the manual labor out of your TIN verification process, whether checking a sales tax number in South Carolina or a VAT number in South Korea. And you create a TIN verification paper trail that stands up to auditor’s scrutiny.
One Invalid TIN Can Cost You—Don’t Risk It
Tax ID verification is an often overlooked step that companies miss. But, especially when selling cross-border, it’s vital for SaaS companies to do their due diligence and make sure every business customer is being truthful about their tax status.
Accepting an invalid tax ID, however inadvertent, can result in blocked tax refunds, audits, and steep penalties and interest.
Don’t skip this crucial step to compliance.
Sphere helps SaaS businesses of all sizes, from first international customer to global conglomerate, to automatically validate EINs, VAT numbers and more, across every market where you sell, all in real time.
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