KSeF Down or Delayed: Offline24 and Emergency Modes Step by Step

Offline modes in KSeF are permanent statute, not a temporary concession. When the system is unavailable, you can issue invoices locally and submit them later. The P_1 issue date on the invoice is the date you wrote it, not the date you submitted it. This preserves the legal date and the applicable NBP exchange rate.

Three offline modes exist, each with different triggers and re-submission deadlines.

Offline24 Mode

When to use: KSeF is temporarily unavailable (timeout, 500/503 errors, maintenance window).

Procedure:

1. Issue the invoice in your invoicing software with today's date as P_1.
2. The software generates the FA(3) XML locally and stores it.
3. Submit the XML to KSeF by the next working day.
4. KSeF assigns the KSeF number and issues the UPO.

Key detail: The invoice carries a Kod II "CERTYFIKAT" QR code in addition to the standard Kod I QR code. The Kod II QR authenticates the issuer via a type-2 certificate and tells the buyer this invoice was issued offline. Your invoicing software must support type-2 certificate generation for offline24 mode to work.

Announced Unavailability Mode

When to use: The Ministry of Finance announces planned maintenance or a known outage period.

Procedure: Same as offline24. Issue locally, submit by the next working day after the announced period ends. The Ministry publishes maintenance schedules on ksef.podatki.gov.pl.

Emergency Mode (Tryb Awaryjny)

When to use: KSeF is completely unavailable for an extended period. The Ministry declares emergency mode.

Procedure:

1. Issue the invoice locally with today's date as P_1.
2. Store the FA(3) XML and the Kod II QR code.
3. Submit within 7 working days of KSeF becoming available again.

Key detail: The 7-working-day window is longer than offline24's next-working-day deadline. Emergency mode is for systemic failures, not transient timeouts.

The Penalty Risk from January 2027

Missing the re-submission deadline is not a problem in 2026. The education period means no penalties for late offline submissions. From 1 January 2027, an invoice issued in offline mode that is not submitted within the deadline becomes an invoice issued outside KSeF. The penalty is up to 100% of the VAT shown (art. 106ni).

This makes deadline tracking a compliance feature. Your invoicing software should:

• Track the submission deadline for every offline invoice
• Alert you when the deadline is approaching
• Auto-submit when KSeF becomes available
• Log the submission timestamp as evidence

What to Do Right Now

1. Configure your invoicing tool for offline24. Test it by issuing a dummy invoice in offline mode and submitting it.
2. Verify type-2 certificate support. Your tool needs a valid type-2 certificate to generate the Kod II QR code. Without it, offline invoices are not legally valid.
3. Monitor ksef.podatki.gov.pl for maintenance announcements. Plan around announced unavailability windows.
4. Set up deadline alerts. From January 2027, every offline invoice has a hard submission deadline with penalty exposure.

This material is information of a general nature and does not constitute legal or tax advice. For a specific situation, verify the current rules or consult a qualified adviser.