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Tax ID Validation
The programmatic process of checking whether a tax identification number (VAT, ABN, UID, or similar) is legitimately registered with the issuing government authority. Tax ID validation confirms both the format and the live registration status of the number.
Tax ID validation is the process of verifying that a tax identification number is registered with the issuing government authority and is currently active. It has two layers: format validation (checking that the number matches the expected structure for its country) and registry validation (querying the live government database to confirm the business is currently registered). Both layers are required for compliance — a correctly-formatted number may belong to a deregistered business.
Why Tax ID Validation Matters for B2B SaaS
For EU cross-border B2B sales, EU VAT Directive 2006/112/EC requires sellers to verify the buyer's VAT number before applying zero-rate treatment (reverse charge). Without this verification, the seller becomes liable for the full VAT amount on the incorrectly zero-rated invoice. Tax ID validation also serves as a first-line due diligence check: the company name and address returned by the registry can be cross-referenced against the buyer's self-declared details.
Tax ID Types by Country
| Country/Region | Tax ID Type | Registry |
|---|---|---|
| EU (27 member states) | VAT number | VIES (European Commission) |
| United Kingdom | VAT Registration Number | HMRC |
| Australia | ABN (Australian Business Number) | ABR (Australian Business Register) |
| Norway | MVA number | Brønnøysund Register Centre |
| Switzerland | UID / MWST number | Zefix (Swiss federal registry) |
The TaxID API validates all five types through a single REST endpoint using the same response format. Format validation errors return instantly without consuming API quota. Registry validation queries the live government database and returns the registered company name and address alongside the validation status.
Validate EU VAT numbers via API
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