According to Polish Ministry of Finance KSeF is not a system for reporting issued invoices; rather, this system is used for issuing them.
A document prepared in the MS D365 accounting systems must be issued using KSeF. Such a document is sent to the system, and it receives the invoice's validity only after receiving the KSeF number, except in exceptions such as offline 24, offline, or emergency mode. This means that an invoice gains the status of legally valid only after being assigned a KSeF number.
In the case of a structured invoice issued online: "An invoice is considered issued on the date it is sent to KSeF . This type of invoice is issued in KSeF in real time. This means that sending the invoice to the online system immediately gives it legal validity, provided that the date in field P_1 matches the date the XML file is sent.
In the case of invoices issued online, strict rules apply regarding the deadline for sending them to the National e-Invoice System. Every electronically generated invoice must be sent to the system on the same day it was issued. Failure to comply with this obligation results in the invoice not being recognized as an online document, and the system will treat it differently.
Ministry of Finance's statement: 'Yes. If you issue an invoice online, it must be sent to the National e-Invoice System (KSeF) on the same day. If you do it the next day, the system will treat it as an invoice issued in offline mode.'
Offline and emergency modes – deadlines for sending invoices to KSeF
In case of technical problems with the KSeF system, the following deadlines apply:
• Offline24 – “The invoice should be sent immediately, no later than the next business day after the day it was issued.”
• Offline (system unavailability) – “The invoice should be sent to KSeF no later than the next business day after the end of the period of unavailability.”
• Emergency mode – “The invoice should be sent to KSeF no later than within 7 business days from the end of the KSeF failure.”
In all these cases, as the Ministry of Finance writes in responses to taxpayers’ questions: “Invoices in the above three modes are considered issued on the date indicated by the taxpayer in field P_1 of the FA logical structure.”
In KSeF, invoices can be issued in:
1. online mode (in real time) or
2. offline mode (an invoice issued outside KSeF with subsequent submission to KSeF).
Offline modes (offline24, KSeF unavailability, emergency mode) require submitting the invoice to KSeF within a specified period and marking it with two QR codes in case it is delivered to the purchaser outside the system, where generating the second code will require a previously generated KSeF certificate (type 2). The KSeF certificate (type 1) is also one of the methods of authenticating in the system.
The deadline for sending an invoice to KSeF therefore depends on the chosen mode: in online mode, the dispatch is immediate, while in offline and emergency modes, the legislator has set maximum deadlines for submitting the documents. Proper completion of field P_1 in the FA structure ensures that the invoice retains the correct issue date.