Warsaw – Poland’s Ministry of Finance has initiated the open testing phase of the KSeF 2.0 National e-Invoice System API on September 30, 2025, marking a significant milestone in the country’s transition to mandatory electronic invoicing.

Testing Environment and Technical Support

The open testing of KSeF 2.0 API enables software testing that facilitates information exchange between the National e-Invoice System and commercially available invoicing systems. This allows financial and accounting software providers to verify how their applications integrate with KSeF 2.0. Start otwartych testów API KSeF 2.0

The testing environment is accessible at ksef-test.mf.gov.pl. All entities conducting integration work and using the KSeF 2.0 testing environment can access technical support on business days from 7:00 AM to 7:00 PM through the contact form at ksef.podatki.gov.pl/formularz/. Start otwartych testów API KSeF 2.0

Comprehensive KSeF 2.0 Manual Released

The Ministry has published a four-part “KSeF 2.0 Manual” that comprehensively covers the National e-Invoice System’s functionality. The first section presents basic system information, including key implementation dates, authentication methods, and detailed explanations of the authorization model. Start otwartych testów API KSeF 2.0

The second part focuses on core KSeF functionalities related to issuing, receiving, and accessing e-invoices. It includes instructions for assigning KSeF numbers to invoices, recommendations for properly completing the FA(3) structure, and technical aspects of submitting invoices to the system in version 2.0. Start otwartych testów API KSeF 2.0

The third section covers additional system functions such as issuing invoices with attachments, offline mode operations, VAT RR invoice procedures, self-invoicing processes, and reporting fraudulent invoices. The final part addresses invoicing by local government units, VAT groups, enforcement proceedings, and public procurement contexts. Start otwartych testów API KSeF 2.0

Implementation Timeline

Poland’s Ministry of Finance has established a detailed roadmap for KSeF 2.0 deployment:

  • October 15, 2025: Pre-production environment (DEMO) becomes available
  • November 1, 2025: Launch of the Certificate and Authorization Module (MCU), through which users can apply for certificates Start otwartych testów API KSeF 2.0
  • November 2025: Release of test and pre-production versions of the KSeF Taxpayer Application
  • January 1, 2026: Launch of the notification module in e-Tax Office for sending invoices with attachments Start otwartych testów API KSeF 2.0
  • February 1, 2026: Ministry of Finance will release the production version of KSeF 2.0 system Start otwartych testów API KSeF 2.0

EU-Funded Digital Transformation

The KSeF 2.0 project is financed under the European Union’s NextGenerationEU program, representing a crucial step in Poland’s tax system digitalization and efforts to combat the shadow economy. The mandatory e-invoicing system is expected to enhance tax compliance, reduce administrative burden, and streamline business operations across the country.

The integration with KSeF 2.0 API is essential for ensuring that financial and accounting systems comply with the mandatory version of the system, scheduled to become operational in early 2026.

https://ksef.podatki.gov.pl/wyjasnienia/start-otwartych-testow-api-ksef-20/