Exchange rate not 1 for an invoice in local currency (ISDOC)
The invoice states no foreign currency, so it is issued in the local currency. Both exchange rate fields (CurrRate and RefCurrRate) must then have the value 1.
What to do now
Who has to fix this?
The issuer of the invoice or their accounting software has to fix this. As a recipient you can usually still read the invoice, but should check the affected details before booking it.
Where this rule comes from
This rule comes from the official rule set of the Czech format ISDOC 6.0.1, not from EN 16931 – ISDOC is not an EN 16931 format. The rules check that credit notes refer to the original invoice and that the currency details are consistent. In the original they have neither identifiers nor English texts; Billvox numbers them ISDOC-01 to ISDOC-04 and explains them.
- Rule ID
- ISDOC-03
- Rule set
- ISDOC (Czech Republic)
- Checked for
- ISDOC (.isdoc and .isdocx)
- Consequence of a violation
- The invoice violates the official ISDOC rule set. Whether the recipient accepts it depends on their own validation system.
Does ISDOC-03 occur in your invoice?
Upload the XRechnung or the ZUGFeRD/Factur-X PDF – the validator shows every violation with the same explanation as here. Free, no login, nothing stored.
Validate your invoice nowGeneral information, not tax or legal advice. As of October 2026. Validation rules: CEN/TC 434 (EN 16931, EUPL 1.2), KoSIT (XRechnung, Apache 2.0), FNFE-MPE/FeRD (Factur-X/ZUGFeRD, Apache 2.0), OpenPeppol AISBL (Peppol BIS), ANAF (CIUS-RO). Explanations: Billvox. Licence notices