System is live
KSeF has been mandatory since 1 February 2026 for large taxpayers. First weeks brought both positive signals and challenges: processing under 2 seconds, 99.5% uptime, but also validation errors and token refresh issues.
For companies entering the mandate in April — start testing now.
EI
Emilia Iwaniuk
Owner of LinTax Accounting Office
Owner of LinTax accounting office, founded from a genuine passion for accounting. She built her experience over many years, working in various business entities and independently managing commercial books. Her work is defined by an individual approach to every client — treating each business as a partner. Accounting is more than numbers — it's real support for business growth.