KSeF FA(3)
The binding Polish structured invoice logical structure used by KSeF 2.0 from 1 February 2026.
Current version and implementation status
How to recognize the profile
Do not rely on the file extension alone. Inspect the root namespace, customization/profile identifiers, version values and authority-specific envelope.
- FA(3) namespace
- NrKSeF
- Podmiot1 and Podmiot2
Production validation stack
- 1FA(3) XSD
Confirm that the document is well formed and structurally compatible with the intended FA(3) syntax.
- 2KSeF logical constraints
Apply semantic and business-rule checks rather than accepting a file merely because it parses.
- 3Tax and identifier rules
Validate currencies, countries, tax categories, units, payment means and other controlled values against the correct release.
- 4Submission response handling
Apply the national, network or authority restrictions that narrow the base syntax.
Common errors and corrective action
Locate the relevant field and rule, correct the source mapping, rerun every validation layer, then preserve the final response.
Locate the relevant field and rule, correct the source mapping, rerun every validation layer, then preserve the final response.
Locate the relevant field and rule, correct the source mapping, rerun every validation layer, then preserve the final response.
Locate the relevant field and rule, correct the source mapping, rerun every validation layer, then preserve the final response.
Countries using or referencing this profile
Questions people ask
What is FA(3)?
The binding Polish structured invoice logical structure used by KSeF 2.0 from 1 February 2026.
How is FA(3) validated?
A production check normally applies FA(3) XSD, KSeF logical constraints, Tax and identifier rules, Submission response handling. Local browser preflight cannot replace the official validation artefacts or authority outcome.
Which version should I use?
The current research note is: FA(3), binding from 1 February 2026. Confirm release notes at the official source before production deployment.
Inspect and prepare FA(3) files
Tax identifier checker
Check the structure of VAT, GST and national business identifiers.
E-invoice schema and version finder
Find the country system, structured format family, likely active version markers and official technical source.
Invoice XML formatter and syntax checker
Format, minify and review well-formed invoice XML locally before deeper profile validation.
Authority and network response decoder
Extract status, identifiers, error codes and messages from common JSON or XML invoice responses.