The Polish Ministry of Finance has published additional technical details on the planned shutdown of KSeF 1.0, ahead of the mandatory go-live of KSeF 2.0. This clarification follows earlier updates outlining the transition timeline, technical rollout and preparation steps for taxpayers and software providers.
In a February update, the Ministry already confirmed the broader planning for the KSeF 2.0 transition and the move towards mandatory use, including key milestones leading into 2026, as explained in Poland KSeF update for February 2026.
Subsequent communications focused on how the rollout would be technically executed and how access to the new system would be organised, as Poland further advanced the KSeF 2.0 rollout and prepared the production environment, covered in Poland advances KSeF 2.0 rollout.
More recently, updated manuals, FAQs and an official roadmap were published, providing detailed guidance on authorisations, certificates and system access, as outlined in New manuals, FAQs and roadmap published for KSeF 2.0.
The latest technical communication now builds directly on that groundwork and confirms the final operational shutdown of KSeF 1.0 and the Module of Certificates and Authorisations (MCU).
What changes during the maintenance window
A technical maintenance break is scheduled from 26 to 31 January 2026 to complete the implementation of KSeF 2.0. During this period, both KSeF 1.0 and the MCU will be unavailable. This clarification is particularly relevant in light of earlier guidance on authorisation and certificate management under KSeF 2.0.
As a result, 25 January 2026 is the final day on which taxpayers can generate KSeF certificates, create authentication tokens or assign authorisations via the MCU. Any actions completed before this deadline will apply directly to the KSeF 2.0 production environment. After the maintenance window, the MCU will no longer be accessible. From 1 February 2026 onwards, certificate and token generation will take place exclusively via the KSeF 2.0 Taxpayer Application.
Permanent shutdown of KSeF 1.0
The Ministry has now confirmed the final cut-off date. On 1 February 2026, KSeF 1.0 and the MCU will permanently cease to function. From that moment, KSeF 2.0 becomes the only available and mandatory e-invoicing system in Poland. This confirmation removes any remaining ambiguity about parallel operation and formally closes the transition phase.
Key dates to be aware of
25 January 2026: Last day to generate KSeF certificates, authentication tokens or assign authorisations via the MCU.
26 to 31 January 2026: KSeF 1.0 and the MCU unavailable due to technical maintenance.
28 January 2026: KSeF 2.0 API available in the production environment for verification purposes.
1 February 2026: KSeF 2.0 goes live, KSeF 1.0 and the MCU are permanently discontinued.
What this means for taxpayers
For companies that have been following the earlier KSeF updates, roadmap publications and documentation releases, this announcement marks the shift from preparation to execution. Taxpayers who have not yet generated certificates, tokens or assigned authorisations via the MCU should complete these steps by 25 January 2026. These configurations will remain valid in the KSeF 2.0 production environment.
From 1 February 2026, permission management, token generation and certificate handling will move entirely to the KSeF 2.0 Taxpayer Application. Companies that postpone these steps until after the maintenance window will need to complete them within the new system. During the maintenance period, taxpayers can still submit ZAW-FA forms to their local tax office to obtain basic KSeF authorisations, including administrative rights for managing access in KSeF 2.0.
Early access to the KSeF 2.0 API
From 28 January 2026, the KSeF 2.0 API will be available in the production environment for verification purposes. This allows taxpayers and software providers to validate user authentication, authorisation lookups, certificate applications and retrieval, and token generation. For organisations finalising their integrations, this verification window provides a final checkpoint before KSeF 2.0 becomes mandatory.
