FG
FacturGate
Rule Deep Dive

EU E-Invoice Pre-Send Gate & Factur-X Converter

Billing & Pricing
PRESET RULE RUNNER

CIUS-FR — French VAT identifier and VAT key

The key is not decorative: (12 + 3 × SIREN mod 97) mod 97. A wrong key is a first-pass rejection, and it is cheap to catch before submission.

  • Recomputes the expected key and reports the mismatch when the key is numeric.
  • Accepts alphabetically-keyed identifiers that exist but cannot be formula-checked.
  • The same offline checker is exposed to agents as check_eu_vat_id.

1 · Target and document

Paste the canonical invoice model (JSON). The gate runs locally in this page — the same deterministic engine the agent tools call.

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