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Check a Norwegian supplier is VAT-registered before you pay the invoice

#mcp #ai #norway #python

Your agent is about to approve an invoice charging 25% MVA. Is the supplier actually in Merverdiavgiftsregisteret? registry-mcp answers from Brønnøysundregistrene / Enhetsregisteret (brreg), by organisasjonsnummer (orgnr, org.nr).

claude mcp add registry-mcp --transport http https://api.foretak.dev/mcp
# or locally, over stdio: uvx registry-mcp
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The prompt

Invoice 2026-0417 from EL ANSARI KONSULT, org.nr 833 285 602, charges NOK 4 000 + 25% MVA. Before I pay: is this supplier VAT-registered, and is the business active?

The call

lookup_company(id="833285602")

{
  "name": "EL ANSARI KONSULT",
  "legal_form_code": "ENK",
  "legal_form": "Sole proprietorship",
  "status": "active",
  "is_active": true,
  "vat_registered": true,
  "vat_registered_at": "2024-04-15",
  "vat_number": "NO833285602MVA",
  "registers": {
    "foretaksregisteret": false,
    "mvaregisteret": true
  },
  "source_url": "https://data.brreg.no/enhetsregisteret/api/enheter/833285602",
  "license": "NLOD 2.0"
}
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Four fields settle it:

  • vat_registered: true — the answer.
  • registers.mvaregisteret — the same fact as the register publishes it, next to the other four registers. Cite this one.
  • vat_number — NO833285602MVA must match the number printed on the invoice. If it doesn't, stop.
  • vat_registered_at: "2024-04-15" — an invoice dated before this charged VAT the supplier wasn't entitled to collect.

status: "active" is the second half of the question. A bankrupt or deleted entity comes back with a different status and a notes entry saying so — the tool docstring is blunt about it: "Read the returned notes before acting on the result."

The two ways this says no

Malformed number. validate_company_id is free and does no network call, so run it on invoice input first:

{
  "input": "833286602",
  "valid": false,
  "normalized": null,
  "reason": "'833286602' is not a valid Norwegian organisasjonsnummer.",
  "hint": "An organisasjonsnummer is nine digits with a MOD11 check digit, e.g. 923609016. If you have a company name instead, call search_company."
}
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valid: false is a normal 200-shaped answer, never an exception. One transposed digit is the usual cause. Fix it, or call search_company with the supplier's name — retrying the same string will not help.

Well-formed, but nobody's. 999999999 passes the MOD11 check and still isn't a company:

{
  "error": {
    "code": "not_found",
    "message": "No entity with organisasjonsnummer 999999999 exists in Enhetsregisteret.",
    "hint": "The number is well-formed, so it may never have been issued or the entity may have been deleted. Call search_company with the company name instead."
  }
}
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A valid orgnr is not an existing company. not_found means never issued, or deleted — hold the payment and ask a human.

Source: Enhetsregisteret, NLOD 2.0. Same JSON over MCP and REST.
Repo: https://github.com/foretak/registry-mcp

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