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Under the mandatory KSeF system, Polish accounting offices retrieve structured invoices directly from the state repository. Taxpayers must still provide documents that remain outside the system, such as foreign invoices, receipts, and simplified bills. Managing access permissions once and tracking the KSeF number assignment date are now the core requirements for smooth cooperation.
The KSeF platform does not send notifications when a supplier issues an invoice, meaning businesses must actively retrieve them. Additionally, because some micro-businesses can issue paper or PDF invoices until 31 December 2026, a complete purchase register requires combining KSeF imports with manual entries.
ФОП (FOP, Ukrainian sole trader) is not the same as JDG, Дія (Diia) will not open a Polish government portal for you, and KSeF is not ЄРПН. Here is a map of the terms that matter, plus what mandatory e-invoicing changes.
On 1 February 2026 the FA(3) schema replaced FA(2) and the production 1.0 API stopped working. This was a new integration contract, not an upgrade. Main API changes: JWT authentication decoupled from sessions, mandatory encryption of every invoice, KSeF certificates, per-invoice batch processing, new duplicate detection, new permission model. Main schema changes: an attachment node, a new "Employee" party role, the 0% rate and the NP code split into specific codes, flexible payment terms, IBAN up to 34 characters. The consequences are commercial, not only technical: invoice numbering, VAT rate mapping, and who in your accounting team can actually see a client's invoices.
issuing your first invoice in KSeF (Poland's National e-Invoicing System) comes down to three things: authenticating, filling in data that matches the FA(3) structure, and submitting. The system then assigns a KSeF number and returns a UPO (official receipt confirmation). Everything else is detail you can learn in a coffee break.
Handing invoicing to your accountant shouldn't mean handing over passwords, banking details or company settings. This article shows how to give your accountant access in Biurko by email, grant exactly the permissions they need, track every action in an audit log, and revoke access in one click. At the end: how a single accounting office runs all its clients from one login.
When you can't send an invoice to KSeF (Poland's national e-invoicing system) — because your internet dropped, your software is lagging, or you simply can't log in — you don't have to stop selling. offline24 mode lets you issue the invoice outside the system and upload it by the next business day. Below we explain the difference between the four special modes (offline24, offline, emergency, and total outage), walk through offline24 step by step, list the common traps, and show what good software handles for you. No panic, no legal jargon.
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