KSeF Validator
Validator
🇵🇱 Validate KSeF Invoices for Poland
KSeFMandatory
KSeF (FA(3)) is required in Poland. Poland launched KSeF (Krajowy System e-Faktur) as mandatory for all B2B transactions on February 1, 2026.
Quick Facts
What We Validate
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)
Invoice Navigator covers 134 KSeF FA(3) rules for Poland.
Common KSeF Errors
Poland E-Invoicing Requirements
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
Validation engineKSeF (centralized government validation)
Required CIUSKSeF XML schema (FA(3) — proprietary, replaced FA(2) in February 2026; not EN 16931)
Government portalKSeF (ksef.mf.gov.pl)
Routing identifierNIP (tax identification number)
PeppolNo — KSeF is a closed national system
KSeF is architecturally different from Peppol-based mandates. If you've built for Belgium or Germany, assume nothing transfers.
FAQ
What is KSeF?
KSeF (Krajowy System e-Faktur) is Poland's National e-Invoice System. From February 2026, all B2B invoices must be submitted as structured XML through KSeF. The system validates each invoice against the FA(3) schema and assigns a unique KSeF ID.
What is the FA(3) schema?
FA(3) is the latest version of Poland's structured invoice schema, replacing FA(2) from February 2026. It defines over 300 fields — some always mandatory, others conditional on transaction type. The XML must conform to the official XSD published by the Ministry of Finance.
How does KSeF validate NIP numbers?
NIP is a 10-digit Polish tax identification number. KSeF validates the format and mod-11 checksum (weights: 6-5-7-2-3-4-5-6-7). The seller's NIP is mandatory — without it, the invoice cannot be issued. The buyer's NIP determines whether the invoice appears in their KSeF account.
When does the KSeF mandate take effect?
February 1, 2026 for large taxpayers (over PLN 200 million annual turnover). April 1, 2026 for all other VAT-registered entities. January 1, 2027 for micro-entrepreneurs with monthly sales under PLN 10,000.
Is this validator free?
Yes. You can validate up to 10 invoices per month for free. No signup required for basic validation.
Learn
E-Invoicing Deadlines
Errors
Poland E-Invoice Errors
Answers
What happens if my e-invoice fails validation?
Learn
Free KSeF Validator
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Poland's KSeF E-Invoicing Mandate Hits All Businesses April 1: What ERP Vendors Must Do Now
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