VAT RR in KSeF: when designating the purchaser creates an obligation

Are you a sole trader purchasing agricultural products from a flat-rate farmer? This guide concerns only the use of KSeF to issue VAT RR and VAT RR KOREKTA invoices. It does not assess any particular farmer’s status or the correctness of an individual tax settlement.

Availability from 1 April 2026

Since 1 April 2026, VAT RR and VAT RR KOREKTA invoices documenting purchases of agricultural products from flat-rate farmers can be issued in KSeF. Using the system for these documents is generally optional, but there is an important exception involving the flat-rate farmer’s designation of the purchaser. The rule and its exception are described by the Ministry of Finance in its section on VAT RR.

Designating the purchaser: an obligation until revocation

If a flat-rate farmer designates the purchaser of agricultural products in KSeF as authorised to issue VAT RR and VAT RR KOREKTA invoices using the system, the purchaser must issue those invoices in KSeF until that designation is revoked.

In this situation, using the system is no longer the purchaser’s free choice. The obligation covers both document types: VAT RR and VAT RR KOREKTA. These conditions are set out in the official Ministry of Finance information.

The separate FA_RR(1) structure

A separate logical structure, FA_RR(1), is provided for VAT RR and VAT RR KOREKTA invoices, according to the Ministry of Finance information on the scope of KSeF.

For organisational purposes, treat this specific case separately from ordinary FA(3) invoices and general self-billing. Do not apply the optional-use rule or the exception concerning designation of the purchaser described here to other invoice types. This guide does not explain their rules or the technical preparation of documents.

An optional organisational checklist

You may use the following checklist as a practical aid:

• Establish whether the document under consideration is a VAT RR or VAT RR KOREKTA invoice concerning a purchase of agricultural products from a flat-rate farmer.
• Check whether the flat-rate farmer has designated your sole-trader business in KSeF as the purchaser authorised to issue VAT RR and VAT RR KOREKTA invoices in the system, and whether that designation has been revoked.

The checklist itself is solely an organisational recommendation, not an additional legal obligation. It does not change the rule described above: where such a designation exists, the purchaser must issue both types of invoice in KSeF until the designation is revoked.

This guide does not cover the procedure for making or revoking a designation, interface operation, VAT deduction conditions, the flat-rate tax refund, issuing or payment deadlines, the content of corrections, or the consequences of incorrectly issued documents.