After the mandate was postponed from its 2024 launch and the publication a few months ago of the final executive acts for KSeF, 2026 marks a radical shift for the Poland economy as e-invoicing becomes mandatory.
Polish companies will be required to issue B2B e-invoices through the national KSeF platform, under a very specific and dedicated format known as FA(3). You will find many more technical details about the mandate in our Poland Country Profile.
The implementation of the B2B mandate required anticipation from Polish companies to manage the transition from the voluntary phase and to take into consideration the following immediate and medium-term stakes.
B2B e-invoicing mandate transition steps and anticipations
Since January 1, 2026, the Polish Ministry of Finance [↗︎] made possible the issuance of attachment along with e-Invoices, but companies are required to submit a notification through the e-Tax Office notifying their intention.
Also, to anticipate the mandate, Polish companies were able to use the production version of KSeF 1.0 to issue e-invoices during the voluntary phase (2025). However, with the implementation of KSeF 2.0 on February 1, 2026, KSeF 1.0 and the MCU (Certificates and Authorizations Module) cease to function, requiring proactive steps from businesses:
- January 25, 2026: This was the final date for businesses to issue voluntary e-invoices via KSeF 1.0 environment and to use the MCU to manage the “three pillars” of their digital identity. After this window closed, the MCU went offline to prepare for the mandatory 2.0 migration. These pillars include:
- Production Tokens: The API keys required for software automation (tokens generated for KSeF 1.0 are not compatible with KSeF 2.0, and new tokens were to be generated).
- Certificates: The digital “seals” necessary for secure authentication and the critical Offline24 mode,
- Authorizations: The legal permissions allowing specific employees or accounting firms to act on a company’s behalf.
- January 28th, 2026: the Ministry of Finance opened KSeF 2.0 API in the production environment, allowing Polish companies to perform final handshake tests, ensuring that user authentication, tokens, and digital certificates are fully operational within the new KSeF 2.0 architecture.
- February 1, 2026: the mandate officially begins for large companies (turnover exceeding PLN 200 million / ~50 M€). As indicated previously, this date also marks the opening of the new KSeF 2.0 Taxpayer Application, replacing the old MCU as the central hub to manage mandatory technical requirements.
For Polish companies that missed the January 25 MCU deadline, the immediate priority on February 1 will be to access the new KSeF 2.0 Taxpayer Application in order to manually generate production tokens and re-grant authorizations.
Next phases and stakes for Polish companies
First, the primary goal for Polish companies is to fully ensure the technical stability and compliance with the new mandate, including management of the various errors and rejections that may occurred during the first days and weeks of the mandate.
Then, on April 1, 2026, the mandate will expand significantly by becoming mandatory for all other VAT-registered businesses in Poland, exception for the smallest VAT-exempt micro-entrepreneurs remaining outside the mandatory scope until the final deadline in January 2027.
Finally, due to the important specificities of the KSeF 2.0 mandate, important adaptations are to be expected in to move toward the implementation of the European Union’s “VAT in the Digital Age” (ViDA) initiative, which aims to “harmonize” Electronic Invoicing & Reporting obligations across all member states.
