Poland’s national e-invoicing system KSeF (Krajowy System e-Faktur) is now mandatory: from 1 February 2026 for large taxpayers with 2024 sales above PLN 200 million, and from 1 April 2026 for all other taxpayers operating in Poland. For a foreign company the key fact is the exemption: without a fixed establishment in Poland you are not required to issue invoices through KSeF, even if you hold a Polish VAT registration. What has changed regardless is your Polish trading relationships — invoices from Polish suppliers now carry KSeF identifiers, and Polish buyers process their purchase invoices through a system your PDF does not enter.
What Is KSeF and When Did It Become Mandatory?
KSeF is the Polish tax administration’s central platform through which all domestic B2B invoices flow as structured XML (the FA schema). Unlike Peppol-style decentralised exchange, KSeF is a clearance model: an invoice legally exists once the system has accepted it and assigned it a KSeF number.
| Date | Obligation | Who it covers |
|---|---|---|
| 1 February 2026 | Issue through KSeF | large taxpayers (2024 sales above PLN 200 million) |
| 1 April 2026 | Issue through KSeF | all other taxpayers established in Poland |
| 1 January 2027 | Penalties apply | up to 100% of the VAT shown on the invoice |
The deadlines and transition rules are covered in depth by VATupdate’s guide and Dudkowiak’s legal overview.
Does KSeF Apply to Foreign Companies?
The deciding test is a fixed establishment in Poland.
- No fixed establishment — the mandate does not apply to you. This holds even with a Polish VAT registration, as long as you have no personnel or infrastructure there.
- Fixed establishment involved in taxable supplies — you comply on the same footing as domestic businesses.
- A Polish subsidiary — fully in scope from its size category’s deadline.
Voluntary participation is open to foreign businesses, and some exporters join so their Polish customers can treat them like a local supplier.
What Changes When You Buy from Polish Suppliers?
This change is already live. Your Polish supplier issues the invoice in KSeF even when the buyer is abroad; you receive it outside the system — by email or an agreed channel — with the KSeF identifier attached. That identifier is the invoice’s proof of authenticity, and it is what your Polish counterparty will reference in any dispute.
If your company already receives structured e-invoices, agree with Polish suppliers on a machine-readable copy: the invoice then lands in your AP workflow automatically instead of arriving as a PDF someone retypes.
What Do Polish Customers Expect from Foreign Suppliers?
Your cross-border sales into Poland stay outside KSeF, so formally nothing changes. In practice, Polish buyers have automated their purchase-invoice handling around KSeF, and a foreign invoice arriving as a structured e-invoice fits that flow far better than a PDF. The simplest channel is the Peppol network — one integration covers Poland’s neighbours too, including Belgium, France and Germany, where similar mandates are live or arriving.
How Should You Prepare?
- Check whether your Polish activity could constitute a fixed establishment: that is the boundary of the KSeF obligation.
- Agree with Polish suppliers on the channel their KSeF invoices reach you through.
- Keep master data clean: your Polish buyer’s NIP number must be correct on every invoice.
- If you plan to establish in Poland, put KSeF integration at the start of the project plan, not the end.
- Note 1 January 2027 — from that date penalties reach up to 100% of the VAT on a non-compliant invoice.
For the wider picture, see the country-by-country timeline in which European countries require e-invoicing and the French mandate that starts this September in France’s e-invoicing mandate.
Summary
KSeF is mandatory in Poland since 1 February 2026 for large taxpayers and 1 April 2026 for everyone else established there, with penalties from 1 January 2027. A foreign company without a Polish fixed establishment does not have to issue through KSeF — but invoices from Polish suppliers now carry KSeF identifiers, and Polish buyers increasingly expect machine-readable invoices in return. A structured e-invoicing channel such as Peppol keeps those relationships running without manual handling on either side.
Explore Finbite’s e-invoicing and Peppol services.
When did KSeF become mandatory in Poland?
On 1 February 2026 for large taxpayers whose 2024 sales exceeded PLN 200 million, and on 1 April 2026 for all other taxpayers established in Poland. Penalties for non-compliance apply from 1 January 2027.
Do foreign companies without a Polish establishment have to use KSeF?
No. The mandate covers taxpayers established in Poland, including foreign companies with a fixed establishment involved in taxable supplies. A Polish VAT registration alone, without personnel or infrastructure in Poland, does not create the obligation.
How do foreign buyers receive invoices from Polish suppliers under KSeF?
The Polish supplier issues the invoice in KSeF and delivers it to the foreign buyer outside the system, for example by email or as an e-invoice, together with the KSeF identifier the system assigned. That identifier serves as proof of the invoice’s authenticity.
What penalties apply for KSeF non-compliance?
From 1 January 2027, penalties can reach up to 100% of the VAT amount shown on the invoice. During 2026 Poland is applying a grace period focused on adoption rather than sanctions.