The Polish KSeF System uses a specific inhouse invoice format based on XML, which is called e-invoice FA. The currently supported version is FA(3).

The Polish FA(3) format is very extensive and covers a wide range of business scenarios some of the less used and edge cases are only supported on demand. In case any of this invoice scenarios apply, do reach out to us. Here a short overview:

• Party Correspondence Addresses
• Supply of goods or provision of services exempt from tax under Article 43 sec. 1, Article 113 sec. 1 and 9 or provisions issued pursuant to Article 82 sec. 3 or pursuant to other provisions.
• Intra-Community supply of new means of transport
• Supply of goods or provision of services taxed under the margin scheme referred to in Article 119 or Article 120
• Support for the EU OSS procedure (Section XII in Chapter 6a)
• Support for excise duty provision (Pursuant to Art. 10 sec. 12 of 6 December 2008 on excise duty)
• Support for designation of the procedure concerning the supply of goods and services
• Advance and Final Invoices

Mandate information

The Polish government introduced the National e-Invoicing System (KSeF) to facilitate electronic invoicing and ensure real-time reporting of transactions. The e-Invoicing model approach that Poland chose is a centralized model.

KSeF will act as a centralized portal for both sending and receiving electronic invoices.

Timeline

February 1, 2026: Mandatory adoption for large taxpayers (annual turnover exceeding PLN 200 million).
April 1, 2026: Full implementation for all remaining taxpayers.

The KSeF Platform

While e-invoices must be transmitted via KSeF, recipients must consent to receive them in this format. If consent is not granted, the issuer is still required to submit the invoice to KSeF but must also deliver a copy through an alternative method, such as email (PDF) or a printed document via regular mail.

The platform follows a credential-based model, meaning only registered users with authorization can access the system. Once authenticated, users can view, issue, receive, and download invoices in a structured format. Taxpayers have the option to grant third-party access, allowing authorized representatives to manage invoices on their behalf.

Businesses can either create invoices directly within the KSeF platform using predefined templates or generate them within their own ERP/accounting system before submitting them to KSeF. The latter option follows standard automatic processes for receiving data, mapping, validating, and communicating with KSeF.

Once submitted, the invoice undergoes automatic validation and a unique KSeF ID number is assigned to every invoice, confirming its authenticity.

All invoices processed through KSeF are archived for 10 years, allowing businesses to retrieve them as needed. The platform provides a secure and centralized repository for this archiving functionality.

Details

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