KSeF 2026: old-style invoicing without penalties, but with 2027 risk

In 2026, the absence of KSeF financial penalties does not mean that KSeF is optional. If a taxpayer is already covered by mandatory structured invoicing, a standard B2B invoice should be issued through KSeF unless an exemption or special mode applies.

An invoice received outside KSeF does not automatically remove the buyer's right to deduct VAT. The Polish Ministry of Finance points to the general VAT deduction conditions and the absence of negative premises, but the document should still be treated as a risk signal.

From 1 January 2027, KSeF penalties are expected to apply. 2026 should therefore be used as an implementation period, not as a reason to postpone the process.

The phrase old-style invoicing can describe three different scenarios: a legal exemption, a legal offline or outage procedure, or a breach of the KSeF obligation.

A legal exemption may include B2C invoices, selected statutory exclusions and temporary 2026 rules for the smallest taxpayers. A special mode may allow issuing outside the system temporarily, but the invoice still needs to be submitted to KSeF within the required deadline.

The risky scenario is a standard PDF or paper invoice sent outside KSeF by a seller who should already issue a structured invoice and has no exemption.

The buyer should not automatically reject VAT deduction only because an invoice arrived outside KSeF. The key questions are whether the transaction is real, whether the general deduction conditions are met and whether any negative premises apply.

In practice, the buyer should keep the order, delivery evidence, payment confirmation and any correspondence explaining why the invoice was outside KSeF.

Scope of mandatory KSeF, podatki.gov.pl - implementation dates, temporary rules and exemptions.

KSeF rules and legal provisions, podatki.gov.pl - information on penalties from 1 January 2027.

KSeF FAQ, podatki.gov.pl - Ministry answers on invoices outside KSeF and VAT deduction.