KSeF offline modes and sending deadlines
An invoice can be issued while it is not yet in KSeF (Poland's national e-invoicing system) and sent later. The technical documentation lists three such modes and a fourth case, total failure.
| Mode | Whose side | When it applies (Polish) | Deadline for sending to KSeF | Deadline, official wording (Polish) | Legal basis as given |
|---|---|---|---|---|---|
| offline24 | the client | Brak ograniczeń (dowolność podatnika) | By the next working day after the issue date | do następnego dnia roboczego po dacie wystawienia | art. 106nda ustawy o VAT (projekt KSeF 2.0) |
| offline | the KSeF system | Niedostępność systemu (ogłoszona w BIP i oprogramowaniu interfejsowym) | By the next working day after the unavailability ends | do następnego dnia roboczego po zakończeniu niedostępności | art. 106nh ustawy o VAT (od 1 II 2026) |
| awaryjny (emergency) | the KSeF system | Awaria KSeF (komunikat w BIP MF i w oprogramowaniu interfejsowym) | Within 7 working days of the end of the failure; a further announcement restarts the count | do 7 dni rob. od zakończenia awarii (przy kolejnym komunikacie licznik liczony od nowa) | art. 106nf ustawy o VAT (od 1 II 2026) |
Total failure
- The invoice may be issued on paper or electronically, without the obligation to use the FA(3) structure: Fakturę można wystawić w formie papierowej lub elektronicznej, bez obowiązku stosowania wzoru FA(3).
- There is no duty to send it to KSeF after the failure ends: Nie ma obowiązku przesyłania faktury do KSeF po ustaniu awarii.
- Such invoices carry no QR codes: Faktury z tego trybu nie są opatrywane kodami QR.
Worked example from the documentation: offline24 with a failure announced
| Date in the example | What happens |
|---|---|
| 2025-07-08 | The taxpayer generates an invoice in offline24 mode (offlineMode = true). The deadline is set to 2025-07-09, the next working day. |
| 2025-07-09 | The Ministry of Finance announces a KSeF failure. The original deadline is moved; the new one is counted from the day the failure ends. |
| 2025-07-12 | The failure is removed. A period of 7 working days for sending the invoice begins. |
| 2025-07-22 | The 7 working days end. The invoice has to be sent by this date, still with offlineMode = true. |
The documentation labels 2025-07-08 as a Wednesday and 2025-07-09 as a Thursday; in the calendar they were a Tuesday and a Wednesday. The dates and the count of 7 working days from Saturday 2025-07-12 to Tuesday 2025-07-22 are consistent.
Other points the documentation makes
- Offline invoices are issued in the FA(3) structure and sent with the parameter
offlineMode: true. - KSeF may itself mark an invoice sent as online as offline, by comparing the issue date with the acceptance date.
- A correcting invoice is sent only after the original document has its KSeF number.
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Questions
Does offline24 mean 24 hours?
The documentation states the deadline as the next working day after the issue date, not as a number of hours.
Which date counts as the issue date of an offline invoice?
Only the value of field P_1 in the invoice file. The documentation says KSeF takes no other value as the issue date.
What happens to the deadline when a KSeF failure is announced while I am waiting to send?
In the offline24 and offline modes the deadline moves: it is counted from the day the last announced failure ended, and is no longer than 7 working days.
Do offline invoices carry QR codes?
Yes, two: KOD I, which lets the invoice be verified in KSeF, and KOD II, which confirms the identity of the issuer. Invoices issued during a total failure carry none.
Source: Tryby offline (KSeF documentation, dated 10.07.2025). Read 2026-11-10.