Poland has set up a national e-invoicing platform: KSeF (Krajowy System e-Faktur). This is a clearance system where invoices are uploaded and approved by the tax authority before they reach the recipient. The system has been made mandatory in phases and now applies to the majority of Polish businesses.

The rollout takes place in three phases:

All VAT-registered businesses must be able to receive KSeF invoices from 1 February 2026, regardless of when they are required to send via KSeF themselves.

Tip: until the end of 2026, no penalties are imposed for errors caused by KSeF. This gives businesses room to set up the system without immediate risk.

KSeF is a pre-clearance system. This means an invoice is first uploaded to the KSeF platform, where the tax authority checks it and assigns a unique KSeF reference number. Only after that is the invoice valid and available to the recipient.

The process step by step:

1. The sender creates an invoice in the mandatory FA_VAT XML format (schema FA(3))
2. The invoice is uploaded to KSeF
3. KSeF checks the invoice and assigns a reference number
4. The recipient retrieves the invoice from KSeF or receives it through their Access Point

A stable internet connection is not always available. That's why KSeF offers an Offline24 mode: invoices may be created offline and uploaded to KSeF by the next business day at the latest. Offline invoices receive a UPO-PDF with an Offline QR code as temporary proof.

Alongside KSeF, there is PEF (Platforma e-Faktur), the Peppol route for e-invoicing in Poland. Both systems coexist:

For domestic Polish B2B invoices, KSeF is the mandatory route. For cross-border invoices (for example, from the Netherlands to Poland), Peppol can be used.

KSeF requires the FA_VAT XML format (schema FA(3)), which was designed specifically for the Polish system. This format supports attachments and has a mandatory QR code.

For the technical connection to KSeF, you need certificates: two sets of .key and .crt files per company (one for online use, one for offline use), including encryption and multi-organization management. These certificates are issued by the Polish tax authority.

Important: never submit certificate files via regular email. Outlook blocks .key and .crt files. Use a secure channel.

eConnect offers a proven KSeF integration in production, currently serving two operational clients (both inbound and outbound, online and offline proven), for customers who send invoices to or from Poland:

• KSeF onboarding: eConnect guides you through the onboarding process, including setting up certificates and the batch processing configuration.
• Batch processing: to avoid rate limiting, eConnect processes invoices in batches (configurable interval)
• KSeF reference number: after clearance, the KSeF reference number is fed back to your ERP system
• NIP number: your Polish VAT number (NIP) is linked to your organization in the eConnect platform

If you invoice a Polish recipient from the Netherlands, you can also use the Peppol route (PEF). eConnect routes automatically based on the recipient's identifier.

Want to set up KSeF integration through eConnect? Get in touch with our team.

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