# UBL-SR-53

Source: https://xmlvalid.com/rules/UBL-SR-53

> CompanyID (VAT Identifier) must be stated when providing the PartyTaxScheme/TaxScheme/ID.

- Level: error
- Rule sets: EN 16931 rules (UBL) 1.3.17, EN 16931 rules 1.3.16 (UBL), EXTENDED-CTC-FR rules (UBL) 1.4.0.04
- Context: `cac:PartyTaxScheme`
- Test: `exists(cac:TaxScheme/cbc:ID) and exists(cbc:CompanyID)`

Validate a document against these rules: https://xmlvalid.com/validate