Short answer: KSeF (the National e-Invoicing System) becomes mandatory in 2026. From then on, business-to-business invoices are issued and received electronically, in a single government system.
What is KSeF?
It's the Ministry of Finance's central platform for issuing, receiving and storing structured invoices (in XML format). Each invoice gets a unique KSeF number.
When does it become mandatory?
Under the current schedule: from 1 February 2026 for large taxpayers (sales above PLN 200m), and from 1 April 2026 for all other businesses.
What changes for your company?
- the end of PDF and paper invoices in B2B – everything goes through KSeF,
- a standardised invoice format (XML) and a KSeF number,
- faster VAT refunds and no more "lost" invoices,
- you'll need to integrate your accounting software with KSeF and grant authorisations.
How to prepare
It's worth getting ready early: adapt your software, decide who in the company has KSeF authorisations, test-issue invoices and tidy up your counterparty data.
How Investya helps
As part of accounting for foreigners we'll set up KSeF-compliant invoicing and take over the ongoing work – in English.
Need a hand?
Book a free consultation – we'll handle it and explain it in plain terms.
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