# UBL-SR-13

> Seller tax registration shall occur maximum once

Checked against Peppol BIS Billing 3.0 2026.5

Canonical: https://einvoicecheck.eu/rules/ubl-sr-13

## Official rule text

Seller tax registration shall occur maximum once

## Why did my invoice fail UBL-SR-13?

The Seller tax registration identifier (BT-32), a seller tax registration under a scheme other than VAT, may occur at most once. In UBL this is the cac:AccountingSupplierParty/cac:Party/cac:PartyTaxScheme whose cac:TaxScheme/cbc:ID is not 'VAT' (e.g. local tax code), and only one such non-VAT entry is allowed.

## Common causes

- Multiple non-VAT tax registrations (e.g. two local schemes) are each emitted as a PartyTaxScheme.
- The same tax code is duplicated under different scheme labels.
- A generic 'TAX' scheme entry is repeated for header and remittance purposes.

## How do I fix it?

```
Keep one non-VAT registration: <cac:PartyTaxScheme><cbc:CompanyID>Local-998</cbc:CompanyID><cac:TaxScheme><cbc:ID>TAX</cbc:ID></cac:TaxScheme></cac:PartyTaxScheme> and remove additional non-VAT PartyTaxScheme entries.
```