- Before 2026, companies can issue some invoices via KSeF and some outside the system, in any proportion.
- Using KSeF for invoicing is voluntary until the obligation starts in 2026.
- Even if a buyer agrees to receive invoices via KSeF, the seller is not required to use KSeF exclusively for that buyer before 2026.
- The obligation to issue invoices via KSeF begins in February 2026 (for most taxpayers, from April 2026).
- Until the obligation takes effect, both structured (KSeF) and traditional (electronic or paper) invoices can be used freely.
Source: ksiegowosc.infor.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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