# HR-BR-9

Source: https://xmlvalid.com/rules/HR-BR-9

> Račun mora sadržavati ispravan OIB operatera (HR-BT-5)

- Level: error
- Rule sets: Croatian eRačun rules (UBL) 13.03.2026
- Context: `cac:AccountingSupplierParty`
- Test: `cac:SellerContact/cbc:ID and u:ctrlOIB(cac:SellerContact/cbc:ID)`

In English: The invoice must contain the operator's valid OIB (HR-BT-5).

## Why it fails

- `cac:AccountingSupplierParty/cac:SellerContact/cbc:ID` is missing: the Croatian extension puts the operator (the person who issued the invoice) there, and the rule wants their OIB.
- The OIB has a typo; it is eleven digits, the last one a check digit (ISO 7064, MOD 11,10), and the rule recalculates it.

## How to fix it

- Add `cac:SellerContact` inside `cac:AccountingSupplierParty`, with `cbc:ID` holding the operator's eleven digit OIB and `cbc:Name` their label (HR-BR-37).

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