The Polish Ministry of Finance has reached another milestone in the KSeF 2.0 implementation roadmap with the publication of the technical API documentation and FA(3) logical structure on 30 June 2025.
This publication enables businesses and software providers to begin preparations for implementing the KSeF 2.0 in the test environment, which aligns with the previously announced timeline towards mandatory e-invoicing.
Technical Documentation Details
The Ministry of Finance has released comprehensive technical documentation, including:
-
FA(3) schema logical structure
-
API technical specifications
-
Overview of critical changes between KSeF API 1.0 and 2.0
-
General explanations of the KSeF 2.0 features
The FA(3) logical structure represents the official version of the mandatory Polish e-invoice schema and was developed through extensive consultation with tax experts, accountants, auditors, software providers, and future users.
Starting 1 February 2026, KSeF 2.0 will become mandatory for all taxpayers subject to the first implementation phase. This date also marks a significant technical transition, as the newly published FA(3) logical structure will officially replace the current FA(2) schema that businesses use in today’s voluntary system.
Confirmed Implementation Timeline
The Ministry has reaffirmed the following implementation roadmap:
-
30 June 2025: API documentation and FA(3) schema published
-
30 September 2025: Test environment for KSeF 2.0 API will be available
-
November 2025: Test version of the KSeF Taxpayer Application browser interface
-
1 February 2026: Mandatory KSeF 2.0 implementation begins
As previously announced, the phased implementation will start with larger businesses on February 1, 2026, followed by other taxpayers in April 2026, with the smallest businesses having until January 2027.
What’s Next?
The legislative process for KSeF 2.0 continues to advance, with regulations expected to be finalized in July 2025. This publication marks an important step toward mandatory e-invoicing in Poland and follows the timeline presented in the Ministry’s implementation roadmap.
Want to understand more about e-invoicing requirements in Poland and how they will impact your business? Read our Sovos e-invoicing in Poland: B2B, B2G, KSeF dedicated webpage.
For future updates on Poland KSeF and similar developments in other countries, subscribe to our Regulatory Analysis page.
