KSeF 2.0 – Structured Invoices in Practice. The New FA(3) Structure as of 1 February 2026

As of 1 February 2026, all e-invoices in KSeF operate under the new logical structure FA(3). This is a significant change that directly affects financial and accounting systems, document workflows, and ERP integrations. In practice, it means that companies must adapt not only their IT tools but also their internal operational procedures.

The new XML structure requires data accuracy to be verified already at the stage of generating invoices in sales and accounting systems. The process of document validation, assigning the KSeF number, and invoice archiving has also changed. Proper technological and process readiness is becoming a prerequisite for the smooth functioning of the entire organisation.

To help companies prepare for the new requirements, Katarzyna Rupp – Tax Advisor at PKF Polska – has prepared a publication addressing the most frequently asked questions regarding structured invoices in KSeF 2.0.

In the publication, she explains, among other things:

• what the XML format and the FA(3) logical structure mean in practice for accounting and sales systems,
• how the process of issuing and validating invoices in KSeF works,
• what technical solutions are necessary for the proper use of the system,
• how invoice receipt, KSeF number assignment, and document archiving are handled.

Today, technical readiness for the KSeF obligation is not only a matter of regulatory compliance but also a key factor ensuring operational efficiency and security – both for accounting departments and for the organisation as a whole.

The PKF Polska team remains at your disposal for advisory services and support in implementing KSeF, as well as in optimising accounting and system processes.

If you would like to ensure that your company is technically prepared for KSeF 2.0, we invite you to read the publication.

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