What you should know about KSeF - a short guide

KSeF is a platform for issuing, receiving, and storing structured invoices in XML format. A fatto to Ministry of Finance, the document has been automatically validated, to a unique ID number KSeF and archived in the central database for up to 10 years.

How should you use KSEF and when?

The legislation provides for three stages of mandatory adoption:

• Active since February 1, 2026 - the largest entity whose sales value, including VAT, exceeds PLN 200 million in 2025,
• from 1 April 2026 - other entrepreneurs (excluding the smallest businesses),
• from 1 January 2027 - the so-called smallest taxpayers, i.e. entrepreneurs with sales of up to PLN 10,000 gross per month.

Protective period: do 31 Desember 2026, a protective period applies during which the Ministry of Finance will not impose penalties for technical errors in the issuance of invoices. However, for substantive errors (e.g., incorrect VAT amounts), taxpayer liability remains.

I am glad to say that if you are not among the largest institutions, it is important to reach KSeF from February 1, 2026. This is because large companies - for example, the biggest fuel station chains - will be required to issue their invoices exclusively in KSeF starting on that date. This means that as a business owner, you will need to download purchase invoices directly from the system in order to book them.

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Will all invoices be issued in KSeF?

No, to B2B. Mandatory will be, among others:

• B2B invoices,
• invoices issued to public institutions,
• advance and corrective invoices.

Excluded from the obligation are, among others:

• B2C import - invoices for consumers (individuals not engaged in business activity) continue to be issued traditionally (paper or electronic) and are not subject to KSeF,
• tax receipt with a VAT ID up to PLN 450 - they may serve as simplified invoices and are excluded from KSeF until 31 December 2026. From 1 January 2027, all invoices - including simplified ones - must be issued in KSeF,
• B2B invoices issued by entities whose total sales subject to mandatory KSEF does not exceed PLN 10,000 gross per month from KSEF on 31 December 2026 or at the first breaching of the limit. AND,
• VAT RR invoices,
• Invoices issued by foreign entities,
• selected cases of VAT-exempt taxpayers.

Does KSeF apply to VAT-exempt entrepreneurs?

Yes, with some truth. Taxpayers who use a subjective or objective VAT exemption are also required to issue invoices through KSeF for transactions that require a structured invoice. A VAT exemption does not exempt them from the XeF obligation.

How to issue invoices in KSeF?

To issue documents in the system, an entrepreneur should:

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- configurare la connessione tra il software di contabilità e XeF,

- generate an access token Certificates and Permissions Module (MCU) - from 1 November 2025, all new permissions will go to MCU,

- assigning the appropriate permissions to employees or the accounting office via MCU.

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Tokens generated in the old KSeF 1.0 will not work in the final KSeF 2.0. If you have old tokens, you must generate new ones in MCU.

Once integrated, the process is standard: the invoice is created in your software, and the system automatically sends the XML file to XeF. After successful validation, the system assigns a KSeF ID (a unique invoice number in the system) and generates a SITZ (Official Receipt Confirmation), which proves that KSeF has accepted and correctly registered the invoice.

Offline mode - a solution for outages

If there is no internet connection or the system is unavailable, the entrepreneur may use offline mode. The request is for a valid issuer certificate.

An offline invoice contains two QR codes - one allowing verification in KSeF and one confirming the authenticity and integrity of the document.

An offline invoice must be sent to KSeF no later than the next business day after issuance.

If the Ministry of Finance announces a KSeF outage via a BIP notice, the entrepreneur may issue invoices in emergency mode - after the outage ends, they have 7 days to send the invoice to KSeF so that it can receive a number and formal validity.

In the case of a so-called total outage - meaning both KSeF and the BIP website are unavailable and the failure has been publicly announced - invoices may be issued outside the system, and once the outage is resolved, there is no obligation to upload them to KSeF.

How to prepare for KSeF?

Introducing KSEF requires not only technical changes but also organizational ones. As an entrepreneur, you should:

• Check system compatibility - check if your invoicing software supports KSeF. If not, plan to switch systems.
• Integration plan - connect your system to KSeF as early as possible to have time for testing.
• Aggiornamento dei dati di - make sure you have correct VAT IDs, addresses, and full details of your suppliers and customers. Errors in invoice data will no longer be correctable via corrective notes - a corrective invoice will be required.
• Train your team - employees responsible for invoicing and accounting must know the new procedures. Consider internal workshops or external training.
• Test the system - the test version of KSeF is available from November 2025, allowing familiarization before mandatory use. Do not leave testing to the last minute.
• Kontakt ditt kontoret - if you feel uncertain, consult specialists who can support the implementation process.

KSeF is not just a technological upgrade but a reconstruction of the entire invoicing system in Poland. Proper preparation will help you take advantage of the opportunity to streamline processes, automate accounting, and reduce errors. However, it requires planning and engagement. The earlier your company starts working with KSeF, the easier it will adapt to the mandatory system in 2026.