Regional spotlight

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• Overview of B2G, B2B and B2C e-invoicing in Poland.
• Key formats, networks and channels you may need to support.
• High-level regulatory and compliance considerations.

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Poland uses KSeF (Krajowy System e-Faktur), the national e-invoicing system, as the centralised platform for all invoice traffic. Both domestic and cross-border invoices are reported to KSeF using the FA(3) structured invoice format defined by the Polish tax authority. For domestic B2B transactions, KSeF is the sole delivery channel — invoices are issued through KSeF, and KSeF handles delivery to the recipient. For cross-border invoicing, invoices are reported to KSeF and additionally sent via the Peppol network when full Peppol address details are provided.

Polish company account registration

When registering a new Polish company via the API, the Polish VAT number must be used as the company identifier. At the moment, company registration requires the vendor to have KYC approval from Maventa. Contact Maventa support to get started.

KSeF authentication

For Maventa to send and receive invoices on behalf of a Polish company, it must act as that company’s authorised technical operator in KSeF. This requires a KSeF authentication token, which the end customer generates once and the partner submits to Maventa.

Submitting the token

Collect the KSeF token from each end customer and submit it to Maventa with POST /v1/services/ksef/tokens. Once the token is active, invoices are sent and received automatically — the end customer does not need to log in to the KSeF portal for day-to-day operations.

How an end customer generates a KSeF token

Share these steps with your end customers. The token is generated in the KSeF 2.0 Taxpayer Application. Logging in supports several methods: the mObywatel app, e-ID, online banking, a Trusted Profile (Profil Zaufany), or a qualified electronic signature or electronic seal.

Sending in Poland

KSeF reporting and delivery

All invoices sent through Maventa for Polish companies are reported to KSeF. When Maventa sends an invoice to KSeF, the invoice is converted to the FA(3) format — the official KSeF structured invoice schema, mandatory from 1 February 2026. For each successfully submitted invoice, KSeF returns a UPO confirmation and the sender can download both the UPO and the cleared FA(3) document via the API.

Domestic invoices are routed exclusively to KSeF by Maventa — the sender does not need to take any additional steps. KSeF acts as the delivery platform and handles forwarding the invoice to the recipient. No other delivery channel is used for domestic traffic.

Cross-border invoices are reported to KSeF and additionally sent via the Peppol network — but only when the full Peppol address details are provided in the sending API metadata. This means both the recipient’s Peppol endpoint ID and the operator’s Peppol identifier must be explicitly included.

Every invoice that is successfully posted to KSeF gets the DELIVERED action, available via GET /v1/invoices/{id}/actions. The DELIVERED action’s channel_details.external_number field contains the KSeF ID.

Email and print delivery

Email and postal delivery (printing) are available as additional delivery channels but are not applied automatically by Maventa. If an invoice needs to be delivered via email or print — for example when Peppol delivery was not possible or no Peppol address was provided — the sender must reroute the invoice to these channels manually. Printing is handled in Finland, and all postal deliveries are sent from Finland.

UPO — official confirmation of receipt

For every invoice successfully submitted to KSeF, Maventa receives a UPO file (Urzędowe Poświadczenie Odbioru — Official Confirmation of Receipt). The UPO is issued by the Polish tax authority system and serves as formal proof that the invoice was received and registered by KSeF.

The UPO typically contains:

• Submission reference and request ID
• KSeF ID (the unique invoice number assigned by KSeF)
• Date and time of receipt
• Processing status (accepted or rejected)
• Sender details
• Hash and integrity reference

The KSeF ID is also available via GET /v1/invoices/{id}/actions in the field channel_details.external_number.

Downloading the UPO and cleared document

Both the UPO file and the CLEARED_DOCUMENT (the FA(3) file as submitted to KSeF) are listed in the files array of the GET /v1/invoices/{id} response. Each file entry includes an id, filename, type, and mimetype.

To download a file, use GET /v1/invoices/{id}/files/{file_id} with the id from the file entry.

Receiving in Poland

For domestic traffic, invoices sent by other Polish companies arrive via KSeF. Maventa retrieves these invoices from KSeF and delivers them to the recipient’s Maventa account, where they can be downloaded. For international traffic, invoices can be received via the Peppol network or directly from other Maventa customers — this requires Peppol SMP registration (see below).

Peppol SMP registration

To receive invoices via Peppol, a Polish company must first be registered in the SMP (Service Metadata Publisher). The SMP registration determines which document formats the company can receive over the Peppol network.

The following document types are registered in the SMP:

Scanning

Scanning is available in Poland via the AutoScan solution.

e-invoicing formats used in Poland

Maventa also supports localised PDF for both sent and received invoices, with the legal invoice data included. The PDF is available in English, Finnish, Swedish, Norwegian (Bokmål and Nynorsk), Dutch, and Polish.