The National e-Invoice System (KSeF) is a digital platform operated by Poland's Ministry of Finance for issuing, receiving, and storing structured invoices in a unified XML format. From April 1, 2026, using this system becomes mandatory for most Polish entrepreneurs.

Implementation timeline

The obligation to issue structured invoices through KSeF is being rolled out in stages:

  • From February 1, 2026 — businesses whose total gross sales (including VAT) exceeded PLN 200 million in 2024.
  • From April 1, 2026 — all remaining businesses, including VAT-exempt taxpayers.

This means the vast majority of Polish businesses must be ready to use KSeF within days.

Exceptions and deferrals

Not all businesses must issue invoices through KSeF immediately:

  • Businesses with monthly turnover up to PLN 10,000 — the obligation to issue invoices through KSeF has been deferred to January 1, 2027. Note: this deferral applies only to issuing invoices. Receiving invoices from counterparties using KSeF has been mandatory since February 1, 2026.
  • Fiscal cash registers — until the end of 2026, shops with fiscal cash registers may issue invoices from the register or receipts with the buyer's tax ID instead of e-invoices. From 2027, all invoices must be issued exclusively through KSeF.

How does KSeF work?

The system operates as follows:

  1. The entrepreneur issues an invoice in XML format compliant with the e-Invoice logical structure.
  2. The invoice is sent to KSeF, where it receives a unique identification number.
  3. The recipient retrieves the invoice directly from the KSeF system.

Every invoice is stored in the Ministry of Finance system, meaning full transaction transparency for tax authorities.

How to prepare

Entrepreneurs should take the following steps:

  • Choose compatible software — ensure your invoicing software supports KSeF, or implement a new solution.
  • Obtain authorization — register in the KSeF system and grant permissions to staff responsible for issuing invoices.
  • Test the integration — the Ministry of Finance provides a test environment for verifying invoice correctness.
  • Train employees — familiarize your team with the new process for issuing and receiving invoices.

Consequences of non-compliance

Failure to comply with the KSeF invoicing obligation may result in fiscal penalties. It is worth noting that the system will ultimately replace traditional paper and electronic (PDF) invoices, making preparation essential for business continuity.

Summary

The mandatory KSeF rollout is one of the most significant tax changes in Poland in 2026. While it requires adapting processes and IT systems, its goal is to simplify document flow and increase tax settlement transparency. Entrepreneurs who have not yet started preparations should act immediately — the April 1, 2026 deadline is just around the corner.