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    Function isValidTaxpayerId

    • Whether the check digit of an eight digit core tax number is consistent.

      Verified against the real tax numbers in NAV's published samples. Note that two of the four tax numbers those samples use (98765432, 87654321) are obvious placeholders and do not satisfy the check — evidence that NAV validates a tax number against its taxpayer registry rather than arithmetically. Treat a failure here as a likely typo, and use queryTaxpayer when you need an authoritative answer.

      Parameters

      • taxpayerId: string

      Returns boolean