KSeF
UPO: what is it?
Official Receipt Confirmation
UPO is an electronic confirmation that the system has accepted a document. For a KSeF invoice it proves acceptance, together with the KSeF number.
Key answers
- What it is
- A document generated by a state system after it accepts an invoice or a return. It contains, among other things, the acceptance date and a reference number. It is worth keeping as proof of filing.
- Who it affects
- Issuers of invoices in KSeF and taxpayers filing returns electronically (e-Deklaracje).
- When
- You receive it once the system has processed the document, usually within moments of sending. Keep it for as long as the document it concerns.
- Where
- In the system to which you sent the document (KSeF or e-Deklaracje), and in the software that sent it.
How it works in Zaksio
Zaksio downloads the UPO from KSeF and stores it with the invoice. For returns you can enter the UPO number manually.
This is information, not legal advice. As of 2026-10. Deadlines and rules may change, so check them in the official source.
