The year 2026 brought the biggest invoicing revolution in Poland in years. From 1 February 2026, the National e-Invoicing System (KSeF) became mandatory for the largest taxpayers whose 2024 sales exceeded PLN 200 million, and from 1 April 2026 for all other businesses. Most companies have therefore been issuing structured invoices for several months now. It is worth remembering, however, that we are currently operating under transitional rules, which expire on 31 December 2026. From the new year, the rules will tighten significantly.
What applies until the end of 2026
The legislator provided a number of facilitations to help companies implement the system smoothly. Until 31 December 2026:
- no financial penalties are imposed for KSeF-related errors — tax authorities do not sanction issuing an invoice outside the system, delays in submitting offline invoices, or technical errors;
- all taxpayers may use the offline24 mode, i.e. issue invoices outside the system and submit them to KSeF no later than the next business day;
- the smallest businesses are exempt — companies issuing only invoices up to PLN 450, with total monthly sales not exceeding PLN 10,000, may continue invoicing the old way;
- invoices from cash registers and receipts with a tax ID treated as simplified invoices remain acceptable.
What changes on 1 January 2027
Penalties for non-compliance
The most important change is the activation of the sanctions regime. For issuing an invoice outside KSeF (where the obligation applied), for failing to submit an offline invoice on time, or for issuing an invoice inconsistent with the official template, the tax authority will be able to impose a financial penalty — up to 100% of the VAT amount shown on the invoice, or up to 18.7% of the gross value for invoices without VAT. It is worth reviewing your invoicing procedures now and making sure all sales channels communicate correctly with KSeF.
The smallest businesses join the system
On 1 January 2027, the exemption for taxpayers issuing small-value invoices expires. This means the e-invoicing obligation will also cover micro-entrepreneurs who have so far remained outside the system. These companies still have a few months to choose a tool — the free KSeF Taxpayer Application, the e-Tax Office, or a commercial invoicing program integrated with the system.
KSeF number in payments
From 2027, businesses will be required to include the KSeF invoice number (or a collective identifier) in bank transfers for structured invoices made between VAT taxpayers, including payments under the split payment mechanism. This will force changes in accounting and banking processes — financial systems must be ready to automatically retrieve these numbers and include them in payment orders.
How to prepare your company for 2027
The remaining months of 2026 are the last chance to organise your processes without the risk of sanctions. In particular, it is worth:
- verifying that all sales invoices — including those issued in the field or outside the main system — reach KSeF within the required deadlines;
- checking the correctness of permissions granted to employees and your accounting office in KSeF;
- testing the flow of purchase invoices, including automatic retrieval of documents from the system;
- preparing payment systems for the obligation to include the KSeF number in transfers;
- for the smallest companies — selecting and implementing a tool for issuing structured invoices.
Our office supports clients in implementing KSeF on an ongoing basis — from granting permissions, through configuring document workflows, to verifying the correctness of settlements. If your company is not yet fully ready for the rules taking effect in 2027, we encourage you to get in touch.