Offline24 mode allows issuing an invoice without connecting to National e-Invoice System (KSeF) in Poland – for example, in the case of a failure or lack of internet access. The invoice must comply with the XML structure and be sent to National e-Invoice System (KSeF) no later than the next business day. If the buyer is a domestic taxpayer with a NIP number, the document must ultimately be delivered via e-Invoice System, not just in a visualisation or email.


