- KSeF 1.0 test environment shuts down on 1 September 2025; users must switch to KSeF 2.0.
- KSeF 2.0 test environment and API testing begin on 30 September 2025.
- API integration with the KSeF 2.0 demo environment is available from 15 October 2025.
- MCU module for certificates and authorizations launches on 1 November 2025; all credentials must be recreated in KSeF 2.0.
- Taxpayer application testing starts 3 November 2025, with pre-production release on 15 November 2025.
Source: taxathand.com
Note that this post was (partially) written with the help of AI. It is always useful to review the original source material, and where needed to obtain (local) advice from a specialist.
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