​

invalid_vat_format

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Example response

{
  "error": {
    "code": "invalid_vat_format",
    "message": "The VAT number format is invalid. Expected format: CC123456789",
    "docs_url": "https://docs.vatly.dev/errors/invalid_vat_format"
  },
  "meta": {
    "request_id": "550e8400-e29b-41d4-a716-446655440000"
  }
}

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What happened?

• The VAT number is missing a country prefix
• The country code is not in the supported countries list
• The number contains only the country code with no digits
• The number does not match the expected format for its country (wrong length, missing required characters)
• The number contains invalid characters after normalization
• The Swiss UID (CHE format) or Norwegian org number fails the MOD11 checksum
• The Australian ABN fails the weighted checksum validation

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Expected formats

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How to fix

1. Include the country code: Always prefix with the country code: NL123456789B01, GB123456789, DE123456789, CHE123456789MWST, NO123456785MVA, AU51824753556
2. Check supported countries: See the full list at Supported Countries
3. Let the API normalize: Don’t strip spaces or dots manually. Send "NL 123.456.789 B01" and the API handles it

# Correct
curl "...?vat_number=NL123456789B01"
curl "...?vat_number=CHE-123.456.789+MWST"
curl "...?vat_number=NO123456785MVA"

# Wrong - no country code
curl "...?vat_number=123456789B01"

# Wrong - invalid MOD11 checksum for Swiss UID
curl "...?vat_number=CHE999999999MWST"

# Also correct - the API normalizes this
curl "...?vat_number=nl+123.456.789+b01"

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Common mistakes

• Forgetting the country code: 123456789 instead of NL123456789B01
• Using lowercase: This actually works fine (the API normalizes to uppercase), but check there’s a country prefix
• Including “VAT” prefix: VAT123456789 is not valid; use the country code instead
• Using GR for Greece: Greece uses EL in the VIES system, not GR
• Missing the MWST/TVA/IVA suffix for Swiss numbers: CHE123456789 alone is not valid; include the suffix (e.g. CHE123456789MWST)
• Missing the MVA suffix for Norwegian numbers: NO123456785 alone is not valid; include MVA (e.g. NO123456785MVA)
• Wrong number of digits: e.g. sending 10 digits for GB (requires exactly 9 or 12)
• Missing the B separator for Dutch VAT: NL numbers require B between the digit groups, e.g. NL123456789B01
• Using an unsupported country: Only EU member states, GB, XI, CH, LI, NO, AU, and SG are supported

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Catching this error with the SDKs

import Vatly, { ValidationError } from '@vatly/node';

const vatly = new Vatly('vtly_live_your_api_key');
const { data, error } = await vatly.vat.validate({ vatNumber: '...' });

if (error instanceof ValidationError) {
  console.log(error.message);
  console.log(error.details); // Array<{ field, message }> | null
}

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Related errors

• missing_parameter - VAT number parameter not provided at all