The KSeF 2.0 API enables testing of software that facilitates the exchange of information between the National e-Invoice System and commercial invoicing systems.
Poland’s Ministry of Finance has released the test (integration) environment of the KSeF 2.0 API programming interface on 30 September 2025.
The KSeF 2.0 API enables testing of software that facilitates the exchange of information between the National e-Invoice System and commercial invoicing systems. It allows financial and accounting software providers to verify how their applications interact with the KSeF 2.0 platform. Integration with the KSeF 2.0 API environment is essential to ensure that financial and accounting systems remain compliant with the mandatory KSeF 2.0 system
The test environment is available at National e-Invoice System – Test environment.
The Ministry of Finance also published the “KSeF 2.0 Manual”, which discusses the important issues related to using the system. The KSeF 2.0 API documentation, enabling integrators to start preparing for system implementation in a test environment, was released on 30 June 2025 and can be accessed at Integrator Support.
Earlier, the Ministry of Finance updated the KSeF portal and introduced a new version of the KSeF 2.0 Manual on 19 September 2025. This updated guide aims to help businesses prepare for the upcoming mandatory national e-invoicing system, which will be implemented in 2026.
Poland’s government published legislation establishing a mandatory national e-invoicing system (KSeF) for large taxpayers, effective from 1 February 2026, and for others, effective from 1 April 2026, in the Journal of Laws on 1 September 2025.
