UBL-SR-53: Tax scheme entries need both a scheme code and a number

What it means

Every cac:PartyTaxScheme holds a party's VAT number (such as BT-31 for the seller or BT-48 for the buyer) or tax number (BT-32). It must contain both a tax scheme code in cac:TaxScheme/cbc:ID, such as VAT, and the number itself in cbc:CompanyID. The check fails if either one is missing.

Why it matters

A number without its scheme cannot be told apart, because the recipient does not know whether it is a VAT number or another tax number. A scheme without a number says nothing. The recipient cannot use either, and the invoice is rejected.

How to fix it

In your invoicing software, check the VAT number and tax number of the seller, the buyer and, if used, the tax representative. If a field is empty, fill it in or clear it so that no empty entry is exported. If you build the XML yourself, give every cac:PartyTaxScheme both cac:TaxScheme/cbc:ID and cbc:CompanyID, or leave the whole cac:PartyTaxScheme out.

The rule as published

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

Where this rule applies