KSeF explained
What is KSeF, and what does it change for you?
The National e-Invoicing System (KSeF, Krajowy System e-Faktur) is the Polish government system for VAT invoices. An invoice is no longer a PDF that you send by email. It is a structured file that goes through the Ministry of Finance.
In one paragraph
An invoice that you issue in KSeF is an XML file in the official FA(3) format. You or your software send the file to KSeF. KSeF checks the file, gives it a unique KSeF number and returns an official receipt called UPO. Only then does the invoice legally exist. Your client also gets the invoice from KSeF. A PDF that you send by email is only a courtesy copy and is not the invoice.
Key dates
- 1 Feb 2026
Large businesses
Companies with more than 200 million zł of sales in 2024 must issue invoices in KSeF. All businesses must be able to receive invoices from KSeF.
- 1 Apr 2026
Everyone else
All other businesses must issue invoices in KSeF. This includes sole traders and VAT-exempt sellers.
- 31 Dec 2026
Grace period for small sellers ends
A seller whose invoices total no more than 10,000 zł gross a month can issue invoices outside KSeF until the end of 2026.
- 1 Jan 2027
Penalties start
From 2027, fines can apply if you do not use KSeF.
These dates come from the Ministry of Finance. For your own case, read ksef.podatki.gov.pl or ask your accountant.
What changes for a sole trader
You need a way into KSeF
Use the free app from the Ministry. Or use software such as Fiskora, which connects to your KSeF account with a certificate.
You cannot delete invoices
After KSeF accepts an invoice, you correct a mistake with a correction invoice. It is now more important to check the invoice before you send it.
Foreign clients: few changes
Invoices to foreign clients also go to KSeF. Your client cannot log in to KSeF, so you still send a PDF to your client. The PDF has a QR code that links to the KSeF copy.
Your costs are also in KSeF
Invoices that other Polish businesses issue to you appear in KSeF. Your accountant needs these invoices for your books.
How Fiskora works with KSeF
Connect Fiskora to KSeF one time. Use a certificate that you create in the KSeF app of the Ministry.
Write the invoice in English or Polish. Fiskora makes the FA(3) file and checks it against the official schema.
Check the PDF on a review page, then send the invoice. Fiskora gets the KSeF number and the UPO. If KSeF is busy, Fiskora tries again.
Fiskora sends the PDF with the KSeF QR code to your client by email. You choose the language.
Fiskora gets the invoices that other businesses send to you from KSeF automatically. Your accountant can see all of them.