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KSeF is Poland’s national e-invoicing system. Hyperline’s integration uses Invopop to send invoices and credit notes in FA(3) XML format for business and government customers.

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Supported invoices

The issuing entity must be based in Poland and have a Polish tax ID (NIP). Complete the customer’s billing address and provide their tax ID when applicable. A domestic 0% VAT rate is not the same as VAT exemption. Do not change the tax treatment of an invoice to bypass a validation error.

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Register your invoicing entity

  1. Open Settings > Invoicing and select your Polish invoicing entity.
  2. Check its company name, billing address, NIP, and contact details.
  3. Enable e-invoicing with KSeF and save your changes.
Hyperline sandbox accounts use KSeF Demo (pre-production). Registration requires a real Polish NIP and an authentication certificate from the KSeF Demo portal.
Older sandbox registrations may have completed automatically in KSeF Test mode, showing Registered without a registration link. These registrations do not switch to Demo automatically. Contact the team through the in-app chat to reset the registration, then complete the Demo certificate steps.
Wait until the registration status is Registered before transmitting invoices. See Invopop’s supplier registration guide for the Demo and production certificate steps. Registration is separate for test and production accounts. See Sandbox and test mode when preparing test invoices.

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Track transmission and download the PDF

Once your entity is registered and transmission is enabled, Hyperline automatically submits eligible finalized invoices. Follow the e-invoicing status on the invoice details page. Hyperline preserves your invoice number, and KSeF assigns a separate reference. Invopop prepares the standard KSeF verification link before submission. That link stays unchanged after acceptance; its availability alone does not confirm that KSeF has accepted the invoice. Once KSeF accepts the invoice, Invopop adds the KSeF number and attaches the official receipt (UPO) to the transmission result. After transmission completes, Hyperline refreshes the stored invoice PDF. The verification QR code appears at the bottom, with the KSeF number below it. If only the number is available, the PDF displays that reference without a QR code. Download the refreshed PDF after transmission completes. A previously downloaded copy does not update. Hyperline also retains the acquisition date returned by KSeF with the transmission result. This is separate from your invoice’s issue date and does not change it.

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Credit notes

For a credit note linked to an invoice transmitted through KSeF, Hyperline includes the original invoice’s KSeF number. If the original transmission is still processing or has not returned that number, Hyperline blocks the credit note’s KSeF transmission until the reference is available.

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KSeF unavailability and failed transmissions

When KSeF has a temporary issue, Invopop automatically retries submission and prevents the same invoice from being uploaded twice. Follow the invoice’s transmission status while these retries run. These retries apply to online transmission. Invopop does not support offline24 issuance or KSeF outage modes in its Poland integration. This integration does not handle the additional certificate verification QR code (CERTYFIKAT), type 2 certificate onboarding, or offline submission deadlines. A processing or failed transmission does not confirm KSeF acceptance. If the transmission fails, review the reported error before retrying. If you cannot determine whether KSeF received the invoice, contact the team through the in-app chat. Mark as transmitted only records a transmission performed outside Hyperline. It does not send the invoice to KSeF, retrieve its KSeF number, or generate a verification QR code. See Mark as transmitted. For general retry guidance, see Troubleshoot accounting and e-invoicing sync errors.