KSeF Mandatory from April 1, 2026
From April 1, 2026, the National e-Invoice System (Krajowy System e-Faktur, KSeF) becomes mandatory for all active VAT taxpayers in Poland. This is a landmark change in how invoices are issued, transmitted, and stored. Paper invoices and PDFs sent by email are no longer sufficient — every VAT invoice must now go through the Ministry of Finance's central system.
Who Is Affected?
- From April 1, 2026 — all active VAT taxpayers (businesses issuing VAT invoices)
- From April 1, 2027 — VAT-exempt taxpayers (entities issuing invoices without VAT)
The obligation applies to both large companies and sole proprietorships. If you are a registered VAT payer and issue invoices, you must now do so through KSeF.
What Is KSeF?
KSeF is a central IT system maintained by the Ministry of Finance through which all structured invoices pass. A KSeF invoice is an XML file in FA(2) format — it is not a visual document but a structured data set.
Key features:
- Unified format — every invoice has an identical XML structure regardless of industry or accounting software
- KSeF number — each invoice receives a unique identification number assigned by the system
- Issue date — the moment the invoice is sent to KSeF (not the date of creation in your software)
- Storage — invoices are stored in KSeF for 10 years; self-archiving is no longer necessary
How to Issue Invoices in KSeF
There are several ways to use KSeF:
- KSeF Taxpayer Application — a free tool from the Ministry of Finance available at podatki.gov.pl
- Accounting software — most popular programs have been updated with KSeF integration
- KSeF API — for businesses with custom IT systems, an API is available for automated sending and receiving
How LinTax Helps with KSeF
LinTax accounting office provides full KSeF support for its clients, including system configuration, software integration, invoice management, and training. Contact us for assistance with the transition.