KSeF is live: first steps and the 10k limit

From 1 April 2026 you issue B2B invoices through KSeF (Krajowy System e-Faktur, Poland's National e-Invoicing System), unless your invoices total no more than 10,000 PLN gross a month (Art. 145m of the VAT Act). What decides it is the invoice issue date, not the period the invoice covers.

The full overview is in our article on KSeF from 1 April. Here is only what matters on day one.

Penalties: the position on 1 April

Sanctions for breaching the KSeF obligation (Art. 106ni of the VAT Act) were due to start on 1 January 2027. Until then, a rejected invoice or a software failure does not lead to a financial penalty.

MF announcement: penalty deferral extended to end of 2027 Draft UD477 — Government Legislative Process

No penalty does not mean you can issue invoices outside the system. An invoice issued in breach of the obligation is formally defective. According to the KSeF 2.0 Handbook, the buyer's right to deduct VAT is in principle preserved (Art. 86 of the VAT Act), but the defect may cause complications, so this is a case where a tax adviser is worth asking. An invoice rejected by KSeF gets no KSeF number and is not a structured invoice.

Art. 106ni Polish VAT Act — penalties

Does the 10,000 PLN threshold cover you?

If the total value of your B2B invoices does not exceed 10,000 PLN gross a month, you can issue them outside KSeF until the end of 2026. The exemption is temporary. How to count the threshold and what happens when you cross it is in our article on the 10,000 PLN threshold.

A March invoice issued in April

You can issue an invoice for a March service until the 15th of the following month, but if you do it on or after 1 April, it goes through KSeF (unless you are under the 10,000 PLN threshold). March invoices issued by 31 March remain valid and do not need to be reissued.

FAQ MF — KSeF 2.0

Three steps for today

1. Log in to KSeF with Profil Zaufany (Poland's trusted digital identity), mObywatel or a qualified electronic signature. If your invoicing software needs a token or certificate, generate it in the Taxpayer Application (tokens and certificates).
2. Check your XML file before sending. KSeF has no validator, so you learn about errors only when an invoice is rejected. You can drop the file into ksefuj.to, with no sign-up and without it leaving your browser. Typical errors are in our article on common validation errors.
3. If you integrate KSeF with your own system, see the FA(2) vs FA(3) comparison. Other questions are in the FAQ.