KSeF for sole traders: what you must do

Since 1 April 2026 KSeF has been mandatory for you whether you are an active VAT taxpayer or VAT-exempt, and B2B invoices go through it only. The exception is sales up to 10,000 PLN a month, until the end of 2026.

KSeF (Krajowy System e-Faktur, Poland's National e-Invoicing System) is a Ministry of Finance platform. Instead of emailing a PDF, your invoice goes into the system, gets a KSeF number and is immediately available to your client. At 2–3 invoices a month your invoicing software does this for you, so the only thing that changes is where the finished document ends up.

Legal position as of 9 October 2026.

Does KSeF apply to my business?

Active VAT taxpayer (you file VAT-7 or VAT-7K): mandatory from 1 April 2026. There is no staying with PDFs for B2B.
VAT-exempt (Art. 113, turnover below 240,000 PLN, not registered as an active VAT taxpayer): no separate timeline, mandatory from 1 April 2026 like active taxpayers, with the same 10,000 PLN threshold. The only permanent carve-out is the EU small-business scheme (Art. 113a), excluded by Art. 106ga(2)(6).
Sales up to 10,000 PLN a month: temporary exemption until 31 December 2026 for every taxpayer, VAT-exempt ones included (Art. 145m). From 1 January 2027 there is no threshold for anyone. The threshold has been amended before, so check the date at ksef.podatki.gov.pl. How it is calculated is covered in our article on the 10,000 PLN limit.

Art. 145m of the VAT Act — 10,000 PLN threshold

The threshold is based on the total gross value of B2B invoices subject to KSeF issued in a given month. Cash register sales, B2C invoices and simplified receipts with a NIP up to 450 PLN do not count.

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 make invoices outside KSeF legitimate. An invoice issued outside KSeF despite the obligation may be treated as issued in breach of the rules, which is a risk for both sides of the transaction.

How to get started: 4 steps

Check that your software supports KSeF 2.0. Ask your provider directly. Fakturownia, inFakt, wFirma and Comarch already do. If yours doesn't, switch.
Issue a test invoice with fictitious data and walk through the whole process, from creation to submission.
Check the file before sending. KSeF rejects an invalid invoice, and a rejected invoice formally does not exist, even if your client got a PDF. You can check the file in the free validator at ksefuj.to, which does not send it outside your browser.
Send an invoice to the MF test environment at ap-test.ksef.mf.gov.pl/web. The data is fictitious and has no legal effect. It shows whether your software connects to the system correctly.

FAQ MF — KSeF 2.0

What if I have no invoicing software?

You don't need paid software. The Ministry of Finance offers two free tools:

Aplikacja Podatnika KSeF (ap.ksef.mf.gov.pl) runs in the browser. You issue invoices through a form, view received ones and manage permissions. You log in with a Trusted Profile (free, set up through online banking, mObywatel or at an office), an e-ID card or a qualified electronic signature. For a few invoices a month it is enough. We compare login methods in our article on KSeF certificates and tokens.
e-mikrofirma is a free MF app for the smallest businesses. It supports KSeF only to a limited extent, so check the current feature list on the MF site before choosing it.

If you use commercial software, ask your provider whether the KSeF update is included in your subscription. It usually is.

What if KSeF is down?

No internet or a brief outage: issue the invoice locally and send it to KSeF by the end of the next business day. The invoice is valid from issue, and you get the KSeF number after submission.
Longer outage: the MF announces an emergency mode. You issue invoices outside the system and deliver them to KSeF within the deadline given in the MF announcement.

Your software should handle both modes automatically, so ask your provider before an outage happens.

What your client and the tax office see

Once KSeF accepts an invoice, it issues a UPO (Official Confirmation of Receipt) with the invoice's KSeF number. A client who runs a business and has a NIP downloads the invoice from their own KSeF access, so you don't need to send anything.

Invoices in KSeF are stored in the Ministry of Finance database and tax authorities can view them, just as they can your VAT returns.

Archive the UPO together with your copy of the invoice. In a dispute with a client or during a tax audit it proves the invoice was registered in the system.

Common questions

What about invoices for consumers (B2C)?

Invoices to private individuals who don't run a business fall outside the KSeF obligation (Art. 106ga(2)(4) of the VAT Act), so you issue them as before, as a PDF or on paper. You can also issue them in KSeF voluntarily. How to get such an invoice to the customer is covered in our article on invoices for private individuals.

What about invoices in a foreign currency?

Invoices in euro and other currencies are also issued in KSeF, and the rules for converting amounts to PLN for VAT purposes don't change. Your invoicing software handles this automatically.

If you want to know what changed in the invoice format, see FA(2) vs FA(3). More answers are in the FAQ.