Poland e-Invoicing Guide

Poland is building one of Europe's most comprehensive centralized e-invoicing systems. The Krajowy System e-Faktur (KSeF) is a government-operated clearance platform where every B2B invoice must be submitted, validated, and assigned a unique number before it gains legal validity. This pre-authorization model gives Poland's tax authority real-time insight into every business transaction.

The system represents a fundamental shift from traditional invoicing: an invoice that has not been accepted by KSeF and issued a UPO (official receipt of submission) simply does not exist in the eyes of Polish tax law. This makes compliance not optional but a prerequisite for conducting business.

Poland's rollout follows a size-based schedule. Large taxpayers (revenue above PLN 200 million) must use KSeF from February 2026, with all other VAT-registered businesses following in April 2026. Micro-entrepreneurs have until January 2027. Crucially, no financial penalties apply during the entire 2026 calendar year, giving businesses a full-year grace period to resolve technical issues.

All VAT-registered businesses must submit their B2B invoices through KSeF using the FA(3) XML schema. The system validates each invoice and returns a unique KSeF number plus a UPO confirmation. Invoices without a valid KSeF number are considered invalid for tax purposes.

The 2026 grace period means businesses can begin using KSeF without risk of financial penalties for non-compliance. Micro-entrepreneurs have an extended deadline until January 2027. Offline provisions exist for system downtime — businesses can issue invoices locally and submit them once KSeF service is restored.

KSeF operates as a centralized clearance platform. Businesses submit invoices via API in the FA(3) XML format. KSeF validates the invoice structure and data, assigns a unique identifier, and issues a UPO (official receipt). The validated invoice is then available for the buyer to retrieve from the platform.

Unlike decentralized models where invoices flow between trading partners directly, KSeF stores every invoice centrally for 10 years. The buyer retrieves their invoices from KSeF rather than receiving them directly from the seller. B2G invoicing already runs through Peppol since 2019, and this infrastructure remains separate from the B2B KSeF system.

Poland has taken a measured approach to enforcement. No financial penalties apply during the entire 2026 calendar year, regardless of when a business's mandatory start date falls. From January 2027, penalties can reach up to 100% of the VAT amount on the invoice, or 18.7% of the gross amount for VAT-exempt invoices.