KSeF Offline24, System Failure and Unavailability — How to Issue an Invoice Step by Step
One of the most practical concerns business owners have about KSeF is a very real scenario: what do you do when there is no internet, the system is down, or you need to issue an invoice immediately?
This is not a hypothetical question about a meteorite hitting the data centre. It is a real situation that happens in business. That is exactly why KSeF includes offline and emergency provisions.
What Is Offline24 Mode?
Offline24 is a solution available when there are difficulties issuing and sending e-invoices to KSeF due to the quality of the transmission network or the lack of an internet connection.
In plain language: if technology decides to cause problems, the lawmakers anticipated a Plan B.
When Can You Use Offline24 Mode?
Offline24 applies when:
- you cannot connect to KSeF in real time,
- there are network problems,
- you need to issue an invoice without delay,
- the system cannot be used in the standard online mode.
This is important because a business owner should not be paralysed simply because the internet connection is having a worse day than usual.
How Does Offline24 Differ from Emergency Mode and KSeF Unavailability?
In practice it is worth distinguishing three situations:
1. Offline24
Used primarily when there are connectivity problems or a technical inability to immediately send the invoice to the system.
2. Emergency Mode (tryb awaryjny)
Covers situations defined in the regulations where the system operates under emergency conditions.
3. Offline Mode — KSeF Unavailability
This relates to the system itself being unavailable. Specific rules apply for submitting invoices afterwards.
From the business owner's perspective the key point is: you need to know which situation you are in and what your obligations are after issuing the invoice.
Does an Offline Invoice Have to Be Submitted to KSeF Afterwards?
Yes. If an invoice was issued in the appropriate offline mode, it must generally be submitted to the system later, in accordance with the applicable rules and deadlines for that mode.
Issuing an invoice outside the standard flow does not close the matter. Think of it as: "issue now, formalise shortly after".
Two QR Codes — What Are They?
This is one of the most important practical details.
Invoices issued offline but not yet submitted to KSeF carry two QR codes:
- the first labelled OFFLINE — provides access to the invoice and allows data verification,
- the second labelled CERTYFIKAT (CERTIFICATE) — enables confirmation of the issuer's identity.
This means that in some offline modes the KSeF certificate plays a significant role.
How to Prepare Your Business for Offline Invoicing
It is best to prepare in advance. In practice, four actions are worth taking:
1. Check whether your invoicing software supports offline modes
Not every system handles this equally well.
2. Establish an internal procedure
Who issues the invoice? Who is responsible for submitting it to KSeF afterwards? Who monitors this?
3. Look into the KSeF certificate
In some scenarios, this element is essential for correctly marking documents.
4. Train the people who issue invoices
Even the best system will not help if an employee clicks "send later" and forgets that "later" does not mean "never".
The Most Common Mistake With KSeF Offline
The biggest mistake is having no procedure at all. Companies often focus on implementing KSeF for the online flow but fail to prepare a scenario for a technical problem.
Yet it is precisely in difficult moments that the robustness of a process is revealed:
- does everyone know what to do,
- does the software support the right mode,
- does the document carry the correct markings,
- is someone responsible for submitting the invoice to the system.
Key Takeaway
KSeF does not mean your business stops when there is an outage. It does mean your business needs a contingency plan.
If you issue invoices regularly, treat offline24 and the emergency rules as a mandatory part of your operational hygiene. It is better to have a plan and never need it than to frantically search for instructions while the client is already waiting for the document.
Tax and e-invoicing rules in Poland change frequently. Always verify current requirements with a licensed accountant or at podatki.gov.pl.