KSeF checklist: 10 things before invoice one

Before your first invoice in KSeF (Krajowy System e-Faktur, Poland's National e-Invoicing System), check the ten items below. Everyone who issues invoices, active VAT taxpayers and VAT-exempt ones alike, has been in the system since 1 April 2026. The exception, until the end of 2026, is sales up to 10,000 PLN a month. Not sure whether that applies to you? Start with our articles on the deadlines and the 10,000 PLN limit.

Legal position as of 7 October 2026.

The checklist

1. Does my software support KSeF and FA(3)?

Since 1 February 2026 the only accepted format for structured invoices is FA(3), and the system rejects FA(2). Ask your provider directly: "Do you support KSeF 2.0 and FA(3)?" If the answer is "no" or "not yet", switch. Fakturownia, inFakt, wFirma and Comarch already support KSeF. We explain the schema differences in FA(2) vs FA(3).

2. Can I log in to KSeF?

You can log in with Profil Zaufany (Poland's trusted identity profile, free, set up through online banking or mObywatel), the mObywatel app, your bank account, an e-ID card (via login.gov.pl), a qualified signature or seal, a KSeF certificate or a token. For most sole traders (JDG) Profil Zaufany is the simplest. Check that login works at ap.ksef.mf.gov.pl. We compare the methods in our article on KSeF certificates and tokens.

3. Have I checked a test invoice?

Create an invoice with fictitious data in your software, then drop the XML file into ksefuj.to. The validator checks compliance with the FA(3) schema and MF requirements, and the file never leaves your browser.

KSeF 2.0 has no built-in validator. You only find out about errors when the invoice is rejected, and a rejected invoice formally does not exist.

The most common errors are covered in our article on FA(3) validation errors.

4. Have I sent an invoice to the MF test environment?

The test environment is at ap-test.ksef.mf.gov.pl. Invoices with fictitious data have no legal effect there, and you confirm that your software connects to KSeF correctly.

5. Do I know what to do when KSeF is down?

Offline mode (no internet or a brief KSeF outage): issue the invoice locally and submit it to KSeF by the end of the next business day.
Emergency mode (the MF announces a longer outage): issue invoices outside KSeF and submit them within 7 business days after the outage ends.

Your software should handle both modes automatically, so ask your provider. More in our FAQ.

6. Does my accountant have access to KSeF?

An accounting firm needs permissions on your behalf. You grant them electronically in Aplikacja Podatnika KSeF 2.0 or through the API. The ZAW-FA form, filed at the tax office, is needed only if you are not a natural person and have no qualified seal, or if your signature or seal carries no NIP or PESEL.

Without granted permissions your accountant cannot see your invoices in KSeF, even if they have kept your books for years.

MF regulation, Journal of Laws 2025, item 1815, §4–5 KSeF 2.0 Handbook, Part I, §3.2.3

7. Do I know the QR code on the invoice?

Invoices from KSeF carry a QR code that lets anyone verify the document. Your software generates it automatically. Just check that it appears on the printout.

8. Do I know where to get help?

The MF runs a helpdesk for KSeF questions, with contact details at ksef.podatki.gov.pl. For tax questions you can call the Krajowa Informacja Skarbowa (National Tax Information) line.

9. Have I told my clients about the change?

Invoices go into KSeF instead of an inbox, and clients need their own KSeF access to retrieve purchase invoices. You can still send a PDF for convenience, but the legal document is the XML file registered in KSeF.

10. Do I have a plan B?

If your software fails, you have two options. Aplikacja Podatnika KSeF is a free MF tool where you issue an invoice through a form (enough for 2–3 invoices a month). The other is the offline mode from point 5, which is a lawful mechanism, not a workaround.

When penalties start

The KSeF obligation for everyone still starts on 1 January 2027. On 16 September 2026 the Ministry of Finance announced that it will extend the deferral of KSeF penalties until the end of 2027. A government draft amending the VAT Act (UD477, version of 22 September 2026, at the inter-ministerial consultation stage) would make Art. 106ni(1)–(3) and (5)–(7) apply from 1 January 2028. It is not law yet.

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

No penalties does not change what a rejection means: an invoice rejected by the system formally does not exist.

If any item came out as "no", start with number 3. The wider context is in our KSeF guide for sole traders.

FAQ MF — KSeF 2.0 Polish VAT Act — Journal of Laws 2025, item 775, as amended