E-invoicing in Poland: the KSeF obligation explained

Poland requires VAT taxpayers to issue invoices through the Krajowy System e-Faktur (KSeF), the Ministry of Finance's central clearance platform. The obligation applies since 1 February 2026 to businesses whose 2024 sales exceeded PLN 200 million (including VAT) and since 1 April 2026 to everyone else; the smallest issuers, whose invoiced sales stay at or below PLN 10,000 gross a month, may keep issuing outside KSeF until 31 December 2026 and join on 1 January 2027. An invoice exists in Poland only once KSeF has accepted the FA(3) XML file and assigned a KSeF number.

Who must issue invoices in KSeF, and from when

Every taxpayer that has to issue an invoice under the Polish VAT Act — active and VAT-exempt, companies and sole traders alike — falls under the obligation. The start came in three steps.

Receiving is not staged: the duty to receive in KSeF has existed since 1 February 2026 for everyone. A buyer with a Polish NIP finds the invoice in KSeF and does not have to accept it; it counts as received when the system assigns its number.

What stays outside the obligation

B2C invoices, invoices from foreign suppliers and a short list of special cases stay outside mandatory KSeF, though most of them may be put through the system voluntarily.

• Consumers (B2C): invoices to private individuals do not have to be issued in KSeF. They may be, but the seller then has to hand the buyer a visualisation with a QR code.
• Purchases from abroad: KSeF is not a reporting tool for incoming foreign invoices.
• Foreign customers: the invoice is issued in KSeF, but a buyer without a Polish NIP cannot fetch it, so the seller delivers a copy carrying the KSeF QR code.
• Simplified invoices from cash registers: receipts with a NIP up to PLN 450 and other cash-register invoices stay outside KSeF until 31 December 2026; from 2027 an invoice to a taxpayer for a cash-register sale must be issued in KSeF.
• B2G is inside: invoices to public bodies are covered, and local-government units must use KSeF too.

Foreign companies with a Polish fixed establishment

A foreign entity registered for Polish VAT is outside the obligation only if it has neither a seat nor a fixed establishment in Poland, or if its Polish fixed establishment does not take part in the supply being invoiced. In every other case the foreign company is treated like a domestic taxpayer and must issue through KSeF.

The Ministry adds that whether a fixed establishment exists "requires an individual assessment of the specific facts" and that it plans separate guidance. That assessment requires professional confirmation. A foreign company that is not obliged may still use KSeF voluntarily, and one with a Polish NIP can act through an appointed person by filing form ZAW-FA.

Transitional reliefs until the end of 2026

2026 is a transitional year: the Ministry confirmed a set of reliefs that run to 31 December 2026, and it describes the year as one of education and support rather than enforcement.

Small-issuer relief (PLN 10,000 a month)

Until 31 December 2026 a business may keep issuing paper or ordinary electronic invoices if the gross value of invoices subject to the obligation stays at or below PLN 10,000 in the month; consumer sales, cash-register sales and simplified receipts do not count. Once the limit is crossed, that invoice and every later one must go through KSeF, and the relief does not return in later months.

No penalties for KSeF errors

Penalties for invoicing errors connected with KSeF are deferred to 1 January 2027.

Cash-register invoices

Invoices, including NIP receipts up to PLN 450, may still be issued from cash registers until the end of 2026.

KSeF number in payments

The duty to quote the KSeF number in payment references, including split-payment transfers, applies to payments made from 1 January 2027.

Offline modes

offline24, offline during announced unavailability and the emergency mode are permanent features, described on the KSeF 2.0 page.

How the system works, in outline

KSeF is a clearance model: the seller's software sends an FA(3) XML file to the Ministry's API, the system validates it against the schema and the sender's permissions, and only then assigns a 35-character KSeF number. The buyer collects the invoice from KSeF; no e-mail, portal or network exchange between the parties is needed for domestic B2B invoices.

Three things follow. The schema is national: FA(3) is not an EN 16931 syntax, so an XRechnung or Peppol BIS file cannot be sent as it is — see the FA(3) schema and European formats. The issue date of an online invoice is the transmission date, provided field P_1 matches it. A rejected file is not an invoice and is corrected and resubmitted; an accepted invoice is changed only by a correcting invoice. The platform itself is explained on KSeF 2.0, the developer view on KSeF integration, and the contrast with Germany's exchange model and Belgium's Peppol network on Peppol vs national networks and the mandate timeline.

How KRONENWERK handles this

NOT YET READY for transmission to KSeF. KRONENWERK generates FA(3) XML for invoices, credit notes and advance invoices and validates it against the Ministry's published schema — SUPPORTED WITH LIMITATIONS — and the KSeF 2.0 module (token authentication, interactive session, FA(3) submission, UPO retrieval and receiving) is built and environment-dependent. It has not been used against the production KSeF. For that reason KRONENWERK currently does not sell subscriptions to Polish companies until production submission has been proven; the country page Poland states the same.

The Polish interface language is available; see e-invoicing in KRONENWERK.