KSeF
FA(3): what is it?
Logical structure of a structured invoice in KSeF
FA(3) is the current template (XML schema) of a structured invoice in KSeF. It defines which fields an invoice has and in what format.
Key answers
- What it is
- An XML schema published by the Ministry of Finance, according to which an invoice in KSeF is built. It contains seller and buyer data, line items, VAT rates, annotations and other fields.
- Who it affects
- Everyone who issues structured invoices in KSeF, and invoicing programs that do it for the user.
- When
- It applies from the moment KSeF accepts invoices in this version. Schema changes are announced by the Ministry of Finance in advance.
- Where
- The schema and documentation are published on the Ministry of Finance's KSeF pages. A regular user does not edit XML, because the software does it.
How it works in Zaksio
Zaksio builds the invoice in the FA(3) structure and validates it before sending.
This is information, not legal advice. As of 2026-10. Deadlines and rules may change, so check them in the official source.
