KSeF 2026 — Polens verbindliches E-Rechnungs-System

KSeF (Krajowy System e-Faktur — National e-Invoice System) is Poland's centralized clearance platform for VAT invoices, operated by the Ministry of Finance. Unlike PEPPOL or Factur-X, KSeF is a pre-clearance system: every B2B invoice must be submitted to KSeF before it is considered legally issued. KSeF assigns each invoice a unique reference number (KSeF number) that the buyer uses for VAT deduction.

For large taxpayers (annual revenue above 200 million PLN): 1 February 2026. For all other VAT-registered businesses: 1 April 2026. Taxpayers exempt from VAT have a further grace period. The original mandatory date (February 2024) was postponed after technical issues with the KSeF system were identified.

KSeF invoices use a Ministry of Finance XML schema — the FA(2) schema (formally JPK_FA(2)). It is a Polish-specific format, not based on PEPPOL UBL or EN 16931. The schema is published on the Ministry of Finance website and updated periodically. Every invoice must include the seller's NIP (Polish VAT number), buyer NIP (if applicable), and be digitally signed before submission.

The Polish Ministry of Finance can impose fines of up to 100% of the VAT shown on an invoice issued outside of KSeF. Additionally, buyers cannot deduct input VAT from invoices not cleared through KSeF, creating strong commercial pressure on suppliers to comply. For repeated violations, penalties and interest accumulate.

Foreign companies registered for Polish VAT are in scope for KSeF mandatory use on the same timeline as Polish companies. Companies not VAT-registered in Poland (selling under the reverse charge / OSS mechanism) are currently not required to use KSeF. The scope may be extended — check the Ministry of Finance guidance for updates.

KSeF generation is on the aiDoks roadmap (Phase E — targeting release before the 2026 mandate). The first version will produce offline KSeF XML for manual upload to the Ministry portal; direct API submission with authentication (qualified e-signature / Profil Zaufany) is planned for a subsequent release. Use the validator today to check KSeF XML files for schema conformance.