KSeF for foreign companies: who must issue e-invoices in Poland?

Poland’s National e-Invoicing System, KSeF (Krajowy System e-Faktur), became mandatory in 2026. If your company is based outside Poland but sells to, buys from, or holds stock in Poland, you have probably been asked: “Are you on KSeF?” This guide explains, in plain English, when a foreign company has to issue invoices through KSeF, when it doesn’t, and what to do either way.

Not tax or legal advice. This is an educational summary of public Ministry of Finance (MF) information as of September 2026. Rules and guidance change; verify on ksef.podatki.gov.pl and with a Polish tax advisor.

The short answer

• No seat and no fixed establishment in Poland: you are excluded from the obligation to issue invoices in KSeF, even if you have a Polish VAT number. You may join voluntarily.
• Fixed establishment in Poland that takes part in the sale: the invoices for that sale must be issued in KSeF, just like a Polish company.
• Fixed establishment in Poland that does not take part in the sale: that invoice is excluded, but may be issued in KSeF voluntarily.
• Polish subsidiary: a Polish-registered company is a Polish taxpayer, and the normal KSeF dates apply to it.

Why the “fixed establishment” test decides

The MF page on the scope of mandatory KSeF lists the exclusions by the status of the parties. Issuing in KSeF is not required for invoices issued:

• by taxpayers who have neither a registered seat nor a fixed establishment in Poland;
• by taxpayers with no seat in Poland but a fixed establishment there, where that establishment does not participate in the supply the invoice covers;
• to private individuals who are not running a business (B2C).

A fixed establishment (in Polish, stałe miejsce prowadzenia działalności gospodarczej) is an EU VAT concept. What counts is a sufficient degree of permanence and a suitable structure of people and technical resources, not a sign on the door or a VAT number. On 28 January 2026 the MF published tax explanations on how to determine a fixed establishment for KSeF purposes. If your answer is not obvious, for example because you have staff, a warehouse, or a contract manufacturer in Poland, get advice. An individual tax ruling is the most reliable way to confirm your status.

Common foreign-company scenarios

1. EU or non-EU seller with a Polish VAT number only

Typical cases: an online seller storing stock in a Polish warehouse, or a company registered for VAT because of local supplies. If there is no fixed establishment, the issuing obligation does not apply. Polish customers cannot force you onto KSeF, though some large buyers may prefer it. Voluntary use is possible and can make life easier for Polish customers who now process everything through KSeF.

2. Foreign company with a Polish branch or team that makes the sale

If the Polish establishment participates in the supply, treat those invoices like a Polish taxpayer’s: structured FA(3) XML, issued through KSeF, from your applicable date (1 February or 1 April 2026).

3. Foreign buyer purchasing from Polish suppliers

Your Polish supplier issues the invoice in KSeF. If you have no seat or fixed establishment in Poland, you are not required to receive it through KSeF; the supplier delivers it the way you agree (for example PDF by email). An invoice delivered outside KSeF should carry a QR verification code so it can be checked against the KSeF record. Tell your suppliers early how you want to receive invoices.

4. Group with a Polish subsidiary

The subsidiary is a Polish company. It must receive via KSeF and issue via KSeF from its applicable date. Head-office systems that create invoices for it, such as a central ERP or shared service centre, must be able to send structured invoices to KSeF.

5. Self-billing with Polish partners

Self-billing arrangements that involve a foreign entity can be awkward in KSeF, because of user permissions and the lack of a built-in approval step. Review these contracts with your advisor rather than assuming the old process still works.

Key KSeF dates (recap)

• 1 February 2026: receiving via KSeF generally mandatory; issuing mandatory for large taxpayers (2024 sales with VAT above PLN 200 million).
• 1 April 2026: issuing mandatory for the remaining taxpayers in scope.
• Until 31 December 2026: transitional relief for issuers whose monthly sales documented by invoices stay at or below PLN 10,000 gross.
• 2027: the deferred small issuers join, and administrative penalties for KSeF breaches are scheduled to start. Verify the current position on the MF site.

More detail: KSeF 2026 dates for SMEs: receive and issue timeline.

Checklist for foreign companies

1. Map your Polish footprint: VAT registration, staff, offices, warehouses, contract manufacturers, subsidiaries.
2. Decide the fixed establishment question with an advisor, using the MF explanations of 28 January 2026. Record the reasoning.
3. List your invoice flows with Poland: sales from abroad, sales by a Polish establishment, purchases from Polish suppliers, self-billing, B2C.
4. Mark each flow as “must issue in KSeF”, “excluded, voluntary possible”, or “receive only”.
5. Tell Polish suppliers how you will receive invoices (email address, format) if you are outside KSeF.
6. If you volunteer or are in scope: check that your ERP or invoicing tool can produce FA(3) XML and connect to KSeF, and decide who authenticates and holds permissions.
7. Prepare a short customer note explaining your KSeF status, so Polish buyers’ accounts payable teams do not reject your invoices by mistake.
8. Re-check yearly or whenever your Polish footprint changes.

FAQ

Official sources (verify live)

• Zakres obowiązkowego KSeF (scope of mandatory KSeF, MF)
• KSeF portal (Ministry of Finance)

Educational materials only. Not legal advice. Not tax advice. Not the official MF / KSeF application. Operator: Ismail Kanto.