Poland's Ministry of Finance has opened API testing for its National e-Invoicing System (KSeF), marking another milestone in the country’s transition to mandatory e-invoicing.
The testing phase began on 30 September 2025 and will run ahead of the February 2026 deadline, when the first wave of businesses must begin using KSeF.
Large taxpayers will be required to use KSeF from 1 February 2026. Smaller companies will follow on 1 April 2026.
To support this transition, the Ministry published the first “KSeF 2.0 Manual” on 19 September 2025. This marks the start of an official information campaign to prepare businesses, public institutions, and taxpayers for mandatory e-invoicing.
First KSeF 2.0 Manual Released
The manual is divided into four parts, focusing on practical steps for adopting and using the system:
- Part I – Getting Started with KSeF
- Explains system basics, registration, authentication methods, user permissions, and rights management.
- Part II – Issuing and Receiving Invoices
- Outlines how to issue and receive e-invoices using the FA(3) structure, assign KSeF numbers, and manage technical submission and verification.
- Part III – Additional Functionalities
- Covers attachments, offline mode, VAT RR invoice rules, self-billing, scam reporting, and collective identifiers.
- Part IV – KSeF in the Public Sector
- Details procedures for government and local authorities, including how NIP reporting and role assignments must be managed.
Future sections of the KSeF 2.0 Manual will expand on topics such as marking invoices, reporting attachments, and transitional provisions. This phased release is intended to help taxpayers prepare step by step for the upcoming mandate.