Starting February 1, 2026, the use of the National e-Invoicing System (KSeF) will become mandatory for the vast majority of VAT taxpayers in Poland. In practice, this means that most invoices will have to be issued and transmitted through KSeF. However, the law provides for several invoicing modes depending on the technical or legal circumstances. What are the differences between them? When and how should each mode be used?
Default mode: Online
This is the standard and most commonly used invoicing mode.
The invoice is generated in the taxpayer’s accounting system and immediately sent to KSeF. The issue date is determined as follows:
- the date of transmission to KSeF, if it matches the date on the invoice, or
- the date stated on the invoice (field P_1), even if the invoice is sent later — however, this carries the risk of penalties if the invoice is considered “offline” and the deadline for sending is missed.
Invoices issued in online mode:
- must be delivered via KSeF to domestic recipients with a Polish VAT ID (NIP),
- can be delivered outside of KSeF (e.g., by email) to foreign entities, consumers, or buyers without a NIP.
Mode: Offline24
This mode is intended for temporary situations where invoice transmission is not immediately possible (e.g., internet outage, field sales).
Key rules:
- the invoice must use the FA(3) structure,
- it may be handed over to the buyer outside of KSeF (e.g., as a PDF),
- it must be sent to KSeF no later than the next business day,
- it must include two QR codes:
- “OFFLINE” – for verifying the invoice in KSeF,
- “CERTYFIKAT” – to authenticate the issuer’s identity.
Limitation: You cannot hand over such an invoice outside of KSeF to a domestic taxpayer with a NIP – they must retrieve it through the system.
Mode: Offline due to KSeF unavailability
This mode applies when KSeF is officially unavailable (e.g., scheduled maintenance announced by the Ministry of Finance in the public bulletin – BIP).
Requirements:
- the invoice must be sent to KSeF within 1 business day after the system is back online,
- the invoice must contain the same two QR codes as in Offline24,
- the invoice can be handed over outside KSeF to foreign clients and consumers.
Mode: Emergency
This mode is activated during a system failure (announced via BIP and KSeF interface).
The taxpayer:
- may issue the invoice outside KSeF,
- must transmit it to KSeF within 7 business days after the failure ends,
- may deliver it outside the system, even to domestic buyers with a NIP (exceptionally),
- the invoice must include two QR codes.
Mode: Total system failure
This applies in extraordinary situations (e.g., national security threats) announced in mass media (TV, radio, internet).
In this case:
- the invoice can be issued in any format (paper or PDF),
- it does not need to be sent to KSeF,
- there is no obligation to use FA(3) structure,
- the invoice does not include QR codes.
Corrective invoices
Whenever you issue a corrective invoice, keep in mind:
- if the correction relates to an invoice issued in offline or emergency mode, the original invoice must first be sent to KSeF before correction,
- corrective invoices are also subject to transmission deadlines, usually no later than the next business day.
Summary
| Mode | When to use | Deadline for sending to KSeF | Additional requirements |
| Online | normal conditions | immediate | none |
| Offline24 | technical issues (e.g. internet outage) | by the end of the next business day | 2 QR codes, not for domestic NIP holders |
| Offline (unavailability) | system maintenance | 1 business day after system restored | 2 QR codes |
| Awaryjny | system failure | 7 business days after failure | 2 QR codes, applies to all buyers |
| Total failure | disaster, war, no BIP access | no obligation | no structure or QR codes required |
Incorrect use of a mode or delays in sending invoices to KSeF may result in penalties — up to 100% of the VAT amount shown on the invoice.
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