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Attribute not allowed in FA(3) invoice XML

What this error means

An invoice element has an attribute that the FA(3) schema doesn't allow at that point. Remove it, and if it carried information you need, put that information in the field FA(3) provides for it.

An attribute is an addition inside the opening tag, like waluta="PLN" in <P_15 waluta="PLN">. The message gives the attribute name, the element it's on and the line number.

Why it's not allowed

In FA(3), data goes in elements, not attributes. The FA(3) XSD schema declares attributes in only two places: kodSystemowy and wersjaSchemy on KodFormularza, and Typ in the table column descriptions in Zalacznik. Any other attribute on an invoice element is a schema error.

FA(3) XSD schema

This rule doesn't cover namespace declarations (xmlns, xmlns:etd, xmlns:xsi). The xsi:schemaLocation attribute on the Faktura element also passes validation.

Where it usually comes from

  • A currency on an amount, for example currencyID="PLN", as in UBL formats. In FA(3) you give the currency once, in KodWaluty.
  • An identifier added by your software, for example id on the Faktura element or on an invoice line.
  • Text language: xml:lang="pl" on a product description.
  • An extra attribute on KodFormularza, for example wersja="3" alongside kodSystemowy and wersjaSchemy.
<!-- ❌ Currency attribute on an amount -->
<P_15 currencyID="PLN">2051.00</P_15>
<!-- ✅ Amount without the attribute, currency in KodWaluty -->
<KodWaluty>PLN</KodWaluty>
...
<P_15>2051.00</P_15>
<!-- ❌ Identifier added by the generator -->
<Faktura id="inv-0142" xmlns="http://crd.gov.pl/wzor/2025/06/25/13775/">
<!-- ✅ -->
<Faktura xmlns="http://crd.gov.pl/wzor/2025/06/25/13775/">

How to fix it

  1. Open the file at the line given in the message and remove the attribute named in it.
  2. Check whether the attribute's value was needed on the invoice. The currency goes in KodWaluty, and your own data to display on the invoice can go in DodatkowyOpis, as a Klucz and Wartosc pair.
  3. If your software generates the file, report the bug to the vendor. Otherwise the attribute comes back with every export.

A missing required attribute, such as KodFormularza without wersjaSchemy, is a separate message, described on the page about missing fields. The attributes on KodFormularza also have fixed values: kodSystemowy="FA (3)", with a space before the bracket, and wersjaSchemy="1-0E". Once you've fixed it, check the invoice again.

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