KSeF (Krajowy System e-Faktur) is the Polish Ministry of Finance's invoicing platform. An invoice issued in KSeF exists in the system first: it gets a KSeF number, and that is the moment the buyer is treated as having received it. Since February 1, 2026, every business in Poland receives its structured invoices this way, whatever its size.
Which dates apply
- February 1, 2026: receiving through KSeF for everyone, and issuing for taxpayers whose sales passed PLN 200 million in 2024.
- April 1, 2026: issuing for all other businesses.
- January 1, 2027: issuing for businesses whose invoiced sales stay at or under PLN 10,000 gross a month. Until then they may keep issuing outside KSeF, starting with the invoice that takes a month past the limit.
The ministry has said that errors made while using KSeF in 2026 will not be penalized.
Getting access
A sole trader signs in to the KSeF Taxpayer Application with Profil Zaufany, mObywatel or a qualified signature. A company starts with its qualified seal or the signature of a person entitled to represent it, and then grants permissions to employees, an accounting office or software through tokens or KSeF certificates. The ministry also publishes a mobile app.
Finding invoices issued to your NIP
In the Taxpayer Application, the list of purchase invoices shows every invoice where your NIP appears as the buyer. Each one can be downloaded as the XML file, which is the legal invoice, or as a PDF visualization with its KSeF number and a QR code that checks it against the system. Accounting and ERP software does the same through the KSeF API, using a token or certificate the business issues to it. KSeF keeps invoices for 10 years.
What KSeF does not hold
Receipts from cash registers (paragony) are not invoices and never reach KSeF, and neither do invoices from foreign suppliers. A receipt with your NIP on it (paragon z NIP) is a simplified invoice up to PLN 450 gross, but it stays on paper. Those documents are the ones to capture separately.
Keeping the rest
Smartbills keeps the documents KSeF leaves out: photograph a paragon in the app, or forward a foreign supplier's invoice to your Smartbills address, and each one is kept with its items, every tax and the total next to the rest of your expenses.