Starting from the VAT settlement for February 2026, taxpayers submitting the JPK_VAT(3) file will be required to use new document identifiers related to the implementation of the National e-Invoicing System (KSeF). 

Each document reported in the VAT register must now include either the KSeF identification number or one of the following new codes: OFF, BFK or DI. 

Importantly, this obligation applies to all taxpayers, regardless of whether they are already required to issue invoices through KSeF. 

Key principles 

The new rules introduce several important requirements: 

• every document recorded in the VAT register must include either a KSeF number or a specific code, 

• the new identifiers apply to both sales and purchase registers, 

• they must be used regardless of whether the taxpayer issues invoices through KSeF, 

• a single document may include multiple codes simultaneously. 

Structured invoices 

Invoices issued through KSeF in online mode must be recorded in the VAT register using the KSeF number. 

Offline invoices 

If an invoice is issued offline or during temporary system unavailability, the taxpayer should report: 

• the KSeF number, if already assigned, or 

• the DI code if the invoice does not yet have a KSeF number at the moment the JPK_VAT file is submitted. 

Once the KSeF number is assigned, the taxpayer must submit a correction of the JPK_VAT file. 

System failure 

Invoices issued during a confirmed KSeF system failure should be marked with the OFF code if the KSeF number has not yet been assigned. 

In this situation, submitting a correction of JPK_VAT after receiving the KSeF number is not required.