KSeF — a practical guide for the entrepreneur

The National e-Invoice System (KSeF) is the government platform for issuing, receiving and storing structured invoices. The system has existed since 2022; in 2026 it becomes generally mandatory.

How do you issue an invoice in KSeF?

An invoice can be issued through a direct integration of your ERP or accounting software (for example PKPortal) with the KSeF API. The invoice must match the logical schema published by the Ministry of Finance.

What does a structured invoice contain?

A structured invoice contains the same elements as a traditional VAT invoice, stored as XML in the FA(2) standard. KSeF assigns a unique reference number (KSeF ID) and keeps the invoice for 10 years.

What are the benefits of KSeF?

• Faster VAT refund (15 days instead of 60)
• No need to archive paper invoices
• Automatic counterparty data checks
• Lower risk of fake invoices

The most common rollout mistakes

Businesses most often go wrong on data-structure preparation, authentication-certificate setup and permission management in the system.