Route: Where it's used
Where tax identification numbers are used
Tax identifiers are referenced in many administrative and regulated workflows. The exact requirement depends on the country and the process. This page describes common contexts where a tax identifier may be requested or recorded.
Public administration
Tax administrations use identifiers to connect filings, payments, correspondence, and taxpayer accounts. They may appear on letters, notices, online portals, and official forms.
- Tax returns and declarations
- Payment reference and allocation
- Identity matching for account access
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Employment and payroll
Employers and payroll processors may use a tax identifier to support withholding, reporting, or social contribution workflows. Requirements vary by country and may involve multiple identifiers.
Banking and regulated onboarding
Banks and regulated organisations may request a tax identifier for compliance reporting or customer due diligence. In cross-border contexts, tax residency reporting can increase the relevance of this information.
Cross-border processes
Some EU or international reporting frameworks reference tax identifiers to reduce ambiguity. The specific identifier accepted depends on the country and the authority involved.
This site does not advise on which identifier to provide in a specific case. Use the official sources for the country and process involved.