KSeF Phase 2: The system works, but companies have problems

In an article for prawo.pl, Arkadiusz Łagowski shared his commentary on the entry into force of the second phase of the KSeF. As of April 1, 2026, the obligation to issue invoices through the KSeF applies to almost all businesses. How does this process work?

In this article, Arkadiusz Łagowski (https://www.prawo.pl/podatki/drugi-etap-ksef-system-dziala-ale-firmy-maja-szereg-problemow,1542019.html)  indicates that the system itself is working and does not detect any signals indicating system problems. However, he emphasizes that “problems resulting from the incompatibility of companies’ accounting systems with the KSeF system remain.” It also happens that an invoice in the KSeF system has the status “accepted” but is not sent to the buyer or becomes invisible. These problems mainly result from incorrect integration of accounting systems with the KSeF system and from erroneous interpretation of API messages. They can also result from incorrect XML encoding of structured invoices and non-obvious errors in the invoice itself (e.g., providing the buyer’s VAT number instead of their Tax Identification Number). It still happens that the buyer receives the same invoice in KSeF and outside the system and must be careful not to record it twice (…)”.

We encourage you to read the entire article, and if you have any questions about the operation of KSeF and how to adapt your company to operate safely with KSeF, please contact us.