What is KSeF, Poland's e-invoicing system?
KSeF, the Krajowy System e-Faktur, is Poland's national e-invoicing system. Businesses established in Poland issue invoices to other businesses as structured files through KSeF, which assigns each one a number and delivers it to the buyer. It became mandatory on 1 February 2026 for the largest companies and on 1 April 2026 for the rest.
Also calledKrajowy System e-FakturNational e-Invoice SystemKSeF 2.0
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- Largest companies
- From 1 February 2026
- All other businesses
- From 1 April 2026
- Penalties
- From 1 January 2027
How KSeF works
KSeF is a clearance system: the seller sends the invoice in the FA(3) structure to the government platform, which validates it and makes it available to the buyer, so the tax authority sees every invoice. Receiving invoices through KSeF has been mandatory for all businesses since 1 February 2026. Issuing became mandatory on 1 February 2026 for businesses whose sales including VAT exceeded PLN 200 million in 2024, and on 1 April 2026 for others. Until 31 December 2026 businesses whose invoiced sales are no more than PLN 10,000 a month may still issue invoices outside KSeF. Financial penalties for failing to issue invoices in KSeF apply from 1 January 2027. Invoices to consumers and invoices from sellers without a Polish establishment are outside the mandate. Fonoa and Avalara connect to KSeF for international groups.
Common questions
When is KSeF mandatory?+
Receiving invoices through KSeF has been mandatory since 1 February 2026. Issuing them became mandatory on 1 February 2026 for businesses with 2024 sales above PLN 200 million and on 1 April 2026 for all others.
Are there exemptions from KSeF?+
Invoices to consumers, and invoices issued by sellers with no seat or fixed establishment in Poland, are outside the obligation. Until the end of 2026, businesses invoicing no more than PLN 10,000 a month can issue invoices outside KSeF.
Are there penalties for not using KSeF?+
Yes, from 1 January 2027, for failing to issue an invoice through KSeF or to send invoices issued offline in time. No penalties apply during 2026.
Software that connects to KSeF
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