Validate KSeF invoices for Poland

KSeF (FA(3)) is required in Poland. Poland launched KSeF (Krajowy System e-Faktur) as mandatory for all B2B transactions on February 1, 2026.

Check a KSeF invoiceChecking is free. The tool detects the profile itself.

At a glance

FormatKSeF (FA(3))

MandateB2B mandatory

PeppolNot connected

FA(3) XSD schema compliance

NIP (tax number) format and checksum validation

Mandatory header fields (Naglowek) completeness

Seller (Podmiot1) identification and NIP presence

Buyer (Podmiot2) identification and NIP/PESEL format

Invoice date (P_1) not in the future

Invoice number (P_2) uniqueness structure

VAT rate and amount calculation consistency

RodzajFaktury (invoice type) enumeration values

Duplicate detection (NIP + invoice type + number)

XSD-001XML not conforming to FA(3) schema

XSD-NIPInvalid NIP format or checksum failure

XSD-P1Invoice date (P_1) is in the future

XSD-REQMissing mandatory field in Fa section

21405Input data validation error (invalid payload)

Phase	Status	Scope
KSeF voluntary	Live (Jan 2022)	All VAT payers (opt-in)
B2B mandatory — Phase 1	Live (Feb 1, 2026)	Large taxpayers (>200M PLN turnover)
B2B mandatory — Phase 2	Live (Apr 1, 2026)	All remaining VAT-registered entities (SMEs, sole proprietors, VAT-exempt businesses)
B2G	Live (Feb 1, 2026)	Included in general KSeF mandate
Financial penalties	Jan 1, 2027	Up to 100% of VAT amount on non-compliant invoices