- KSeF is introducing new, unified addresses for its environments as part of preparations for KSeF 2.0 and enhanced security.
- The change is technical and does not affect API functionality; old addresses will remain active during a transition period.
- New addresses will be available from 15.12.2025; integrators should switch test environments by 10.01.2026.
- Automatic redirects from old to new addresses will start after 10.01.2026; manual updates may be needed if redirects are unsupported.
- Old addresses will be fully disabled on 17.01.2026, and from 01.02.2026 only new addresses will be used in production; MCU service address remains unchanged.
Source: gov.pl
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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