Poland extends its KSeF penalty relief, but the KSeF mandate 2027 stands

The Hague, 5 October 2026. The Polish Ministry of Finance is postponing penalties for errors in the use of KSeF, the national e-invoicing system, until 31 December 2027. The KSeF mandate 2027 is unaffected: from 1 January 2027, KSeF is mandatory for all businesses in Poland. For any company that invoices a customer in Poland, or has an establishment or VAT registration there, the postponement is no reason to pause preparations.

KSeF penalties postponed: the facts

The Ministry announced the decision on 16 September 2026. The existing penalty relief, which ran until the end of 2026, is extended by one year. The Ministry is initiating a legislative amendment for this, so the extension still has to be enacted into law.

The aim is to give the smallest businesses, for which KSeF becomes mandatory on 1 January 2027, more time to learn the system and adapt their processes without financial risk. Minister of Finance Andrzej Domański: “KSeF is a project that from the start has been, and still is, widely consulted with entrepreneurs, industry organisations, tax advisers and software providers. We listen to the voice of the market and respond to the needs that are reported.”

The relief is explicitly not a free pass. According to the Ministry, the Polish National Revenue Administration (KAS) will act where invoices are issued outside KSeF (except in cases defined by law) and will examine whether not using the system leads to unreliable tax settlements.

Context: how KSeF is phased in

According to the Ministry of Finance, the roll-out runs in stages:

• 1 February 2026: issuing obligation for companies with 2024 sales above PLN 200 million; from that date, all businesses receive invoices through KSeF.
• 1 April 2026: issuing obligation for all other businesses.
• 1 January 2027: end of the transitional arrangements, including those for the smallest businesses with monthly invoiced sales of up to PLN 10,000. From then on, the obligation applies to everyone.

Important for suppliers outside Poland: according to the Ministry’s tax explanations of 28 January 2026, the issuing obligation does not apply to taxpayers without a registered seat or fixed establishment in Poland, nor to a Polish fixed establishment that does not participate in the supply concerned. A fixed establishment that does participate must issue its invoices through KSeF itself. Whether a fixed establishment exists is a factual assessment; a Polish VAT registration alone does not decide it, but it is a clear signal to look into it carefully.

What it means and what you need to do now

Whether your company supplies Polish customers from the Netherlands, Belgium, Luxembourg, Germany or France: treating KSeF as a purely Polish matter risks invoices getting stuck at your customers. When invoicing Polish customers, make sure the following is in place before 1 January 2027:

1. Establish your position. Document whether you have a registered seat or fixed establishment in Poland and whether it participates in your supplies. If in doubt, have this reviewed by a Polish tax adviser.
2. With a participating Polish fixed establishment: make sure it issues invoices through KSeF, using software or a service provider that connects directly to KSeF (sometimes called a KSeF access point in the market).
3. Without a fixed establishment: you will generally invoice outside KSeF. Document why, so you can answer questions from customers or KAS.
4. Align with your Polish customers. They process domestic purchase invoices through KSeF and yours separately. Ask which format and channel they expect, for example a Polish e-invoice, Peppol or PDF, and which data must appear on the invoice.
5. Check intra-group flows. If a Polish group company invoices your organisation outside Poland, it makes the structured invoice available in a manner agreed with you. Put that agreement in writing.
6. Test before the deadline. The penalty relief gives room to fix errors, but invoices issued outside KSeF remain under scrutiny. Plan a test period in the fourth quarter of 2026.

Sources

1. Polish Ministry of Finance: Przedłużenie odroczenia kar za błędy w stosowaniu KSeF do końca 2027 r. (16 September 2026)
2. Polish Ministry of Finance: Krajowy System e-Faktur, plan wdrożenia
3. Polish Ministry of Finance: press conference ahead of the KSeF launch (16 January 2026)
4. Polish Ministry of Finance: Objaśnienia podatkowe on KSeF (28 January 2026)
5. Sovos: Poland Ministry of Finance extends KSeF penalty relief until end of 2027
6. Grant Thornton Poland: Krajowy System e-Faktur, kto jest obowiązany do wdrożenia KSeF

For more background, read our earlier articles on what mandatory KSeF e-invoicing means for international trading partners and on the first weeks of KSeF in 2026. Looking for a solution that covers both Peppol and the KSeF mandate 2027? The overview of Peppol suppliers lets you filter by country coverage and features.