Poland KSeF: Mandatory e-Invoicing from 2026

What is KSeF?

KSeF stands for Krajowy System e-Faktur, the National e-Invoicing System run by the Polish Ministry of Finance. It is a centralised platform through which structured e-invoices are issued, received, and archived.

KSeF was first introduced on a voluntary basis in January 2022. The mandatory roll-out was delayed twice before being legislated in final form. On 27 August 2025, the Polish President signed the amendment to the VAT Act establishing KSeF as the mandatory national e-invoicing platform from 1 February 2026.

The current generation of the platform, known as KSeF 2.0, forms the basis for the 2026 mandate.

Who is in scope, and when

The rollout happens in three waves based on turnover.

1 February 2026: large taxpayers with 2024 turnover above 200 million PLN (VAT inclusive) must start issuing B2B invoices through KSeF in the production environment. Reporting-year turnover was originally to use 2025 data, but the final legislation moved to 2024 figures so large taxpayers have clearer notice of inclusion.

1 April 2026: all other VAT-registered businesses in Poland must issue B2B invoices through KSeF, regardless of size, except micro-entrepreneurs.

1 January 2027: micro-entrepreneurs join the mandate. From this date, KSeF covers both B2B and B2G transactions across every VAT-registered business.

How KSeF works

KSeF uses a centralised platform model. The seller submits the invoice as structured XML in the national FA(2) schema through the KSeF API. The platform validates the data, assigns a unique KSeF ID number, and makes the invoice available to the buyer through the same platform.

The buyer does not receive the invoice via email or EDI. Instead, they retrieve it from KSeF using their own credentials. This moves Poland from a post-audit model to a centralised platform model, closer to Italy's SDI than to a PEPPOL-based decentralised exchange.

Invoice archival is handled by KSeF itself for 10 years. Businesses still need to maintain their own retention for commercial, audit, and IFRS purposes, but the tax-law archive obligation is discharged by the platform.

Penalties

The legislation allows the tax authority to impose fines of up to 100% of the VAT amount shown on an invoice issued outside KSeF. Where no VAT is shown, for example on zero-rated exports, the fine can reach 18.7% of the total invoice value. These are administrative penalties under Article 106ni of the VAT Act, with the authority retaining discretion to adjust for severity.

Crucially, the penalty provisions apply only from 1 January 2027. No financial penalties will be imposed during 2026 for KSeF-related invoicing errors. The whole of 2026 is a grace period, giving businesses time to onboard and stabilise their KSeF workflows before enforcement begins.

A separate PLN 500 penalty applies from March 2026 for errors in KSeF invoice designations within SAF-T files, but this is a compliance fine tied to SAF-T reporting, not a KSeF non-issuance penalty.

Related reading

For country-level data and timeline detail, see Poland on e-Invoice.app. For how centralised platforms compare to clearance and PEPPOL, see mandatory B2B e-invoicing countries.