KSeF from 1 April 2026: who must use it

From 1 April 2026 every taxpayer who issues B2B invoices, active VAT payer or VAT-exempt, issues them through KSeF (Krajowy System e-Faktur, Poland's National e-Invoicing System). The exceptions are invoices to consumers and, until the end of 2026, sales up to 10,000 PLN a month. Legal position as of 9 October 2026.

What KSeF is

KSeF is a government platform for issuing and receiving structured invoices. Instead of emailing a PDF, you issue an XML file in a strictly defined format and send it to the Ministry of Finance system. The invoice is archived, gets a unique KSeF number and is immediately available to your customer.

KSeF has run since 2022 as a voluntary system. It became mandatory for the largest companies on 1 February 2026 and for all other taxpayers on 1 April 2026.

MF FAQ — KSeF 2.0

Deadlines and who is covered

The schedule comes from Art. 145m ff. of the Act of 11 March 2004 on goods and services tax (Journal of Laws 2025, item 775, as amended):

The obligation covers everyone who issues invoices, active VAT payers and VAT-exempt taxpayers alike: sole traders (JDG), companies, professionals, freelancers, and landlords of commercial property.

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

Sales up to 10,000 PLN a month

If your monthly sales do not exceed 10,000 PLN, you can issue invoices outside KSeF until 31 December 2026, whatever your VAT status (Art. 145m). From 1 January 2027 there is no threshold for anyone. How to count the threshold is in our article on the 10,000 PLN threshold.

How issuing an invoice works

1. You issue the invoice in software that supports KSeF.
2. The software generates an XML file in the FA(3) format and sends it through the Ministry of Finance API.
3. KSeF assigns the invoice a KSeF number.
4. The customer receives the invoice from their KSeF account or through an integration.

Invoices to consumers (B2C), meaning individuals not running a business, fall outside the KSeF obligation. You can issue them on paper, as a PDF or voluntarily in KSeF. The details are in our article on invoices for private individuals.

FA(3) is the official XML schema for structured invoices, in force since 1 February 2026. It replaced FA(2), used since September 2023. The Ministry of Finance describes every field in the FA(3) information sheet: what is mandatory, its data type and the permitted values. The schema is public at https://crd.gov.pl/wzor/2025/06/25/13775/. Your invoicing software usually generates the XML, but if you use the API integration you need to know FA(3).

KSeF 2.0 has no built-in validator, so you learn about errors only after sending. A rejected invoice does not exist: it gets no KSeF number, which means a payment delay, a correction and a risk with the issue deadline. You can check the XML beforehand in the ksefuj.to validator, which runs in your browser and does not upload the file. Typical errors are in our article on common FA(3) validation errors.

Penalties for invoicing outside KSeF

The basis is Art. 106ni of the VAT Act. The penalty applies to not issuing an invoice in KSeF, to issuing an invoice that does not match the template during an outage or in offline24 mode, and to sending offline invoices and Art. 106nf and 106nh invoices late. It is up to 100% of the VAT on the invoice, or up to 18.7% of the gross amount when the invoice shows no VAT. The VAT Act may also limit the buyer's right to deduct VAT from such an invoice, so both sides carry risk.

Art. 106ni of the VAT Act — penalties MF announcement: penalty deferral extended to end of 2027 Draft UD477 — Government Legislative Process

If you issue an invoice in emergency mode but deliver it to KSeF within the required deadline, the sanction should not be imposed (Art. 106ni of the VAT Act).

Invoices excluded from KSeF

The exclusions come from Art. 106ga(2) and Art. 145n of the VAT Act and the MF regulation (Journal of Laws 2025, item 1740). They include, among others:

• permanently (Art. 106ga(2)): invoices from sellers with no seat or fixed place of business in Poland (point 1) and from sellers whose fixed place of business in Poland does not take part in the supply (point 2), invoices under the OSS and IOSS special procedures (point 3), invoices to individuals not running a business (point 4) and invoices from taxpayers using the Art. 113a exemption (point 6),
• permanently (MF regulation, § 2): among others, invoices for toll motorway travel and single tickets for passenger transport,
• cash register invoices and receipts with a NIP up to 450 PLN (or 100 EUR), until 31 December 2026 (Art. 145n of the VAT Act). From 1 January 2027 a cash register can no longer issue invoices, and a receipt with a NIP stops counting as a simplified invoice.

VAT RR invoices, issued when buying agricultural produce from a flat-rate farmer, can be issued in KSeF voluntarily from 1 April 2026. MF: KSeF legal basis and key dates

An invoice to a buyer with no seat or fixed place of business in Poland (e.g. a foreign business) is not excluded: you issue it in KSeF and hand it over in an agreed way, e.g. as a PDF with a QR code (Art. 106gb(4) and (5)). The same goes for a buyer without a Polish NIP. We cover this in our article on foreign invoices in KSeF. Before excluding a specific invoice from KSeF, check the provision at the source or ask a tax adviser.

Art. 106ga and 106gb of the VAT Act — exclusions and handing over the invoice MF regulation on cases with no structured invoice obligation (Journal of Laws 2025, item 1740) Art. 145n of the VAT Act — cash registers KSeF 2.0 Handbook, Part I, p. 14 (cash registers and receipts with a NIP from 2027)

KSeF modes

• Online. The standard mode: the invoice goes to KSeF immediately and gets its number at once.
• Offline24. When you have no internet or KSeF is briefly unavailable, you issue the invoice locally and send it without delay, no later than the end of the next business day. The invoice is valid from issue; you get the KSeF number after sending. It is for exceptional situations.
• Emergency. In a prolonged KSeF outage the Ministry of Finance declares emergency mode. You then issue invoices outside KSeF, meeting strict formal requirements, and send them no later than 7 business days after the outage ends.

Details are in our guides.

How to prepare

1. Check whether you are covered. You issue B2B invoices as an active VAT payer or VAT-exempt: yes, unless you stay within 10,000 PLN a month (until the end of 2026).
2. Check your software. It must generate FA(3) XML, send invoices through the API and receive purchase invoices. Fakturownia, inFakt, wFirma, Comarch, Symfonia and others support it or are rolling it out. Confirm with your vendor.
3. Set up authentication: a qualified electronic signature, Profil Zaufany (via ePUAP or mObywatel) or an authorisation token for API integrations. Your NIP must have permissions in the system.
4. Test in the test environment at https://ap-test.ksef.mf.gov.pl/web/. Invoices with fictitious data have no legal effect.

Other questions are in the FAQ. If you already have an XML file, check it in the validator before the first submission.