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KSeF Setup Guide

KSeF (Krajowy System e-Faktur) is the Polish mandatory national e-invoicing system. It requires invoices issued in Poland to be transmitted and stored electronically through the government-run platform, except, among others, invoices to a private person not carrying on a business (art. 106ga ust. 2 pkt 4 of the VAT act).

Follow the steps below to obtain the credentials needed to connect Invoicerr to KSeF.

1. Obtain your NIP number​

Your company must have a Polish NIP (Numer Identyfikacji Podatkowej) tax identification number.

  • If you are already registered for tax purposes in Poland, your NIP is your tax ID.
  • If you are a foreign company, you may need to register for a Polish NIP through your local tax office or appoint a Polish fiscal representative.

2. Obtain KSeF access tokens via the Ministry API​

KSeF uses an API-based authentication model. To send invoices you need:

  • NIP — your Polish tax ID
  • Invoice token or authorisation certificate (depending on the integration method)

Get a KSeF token​

Invoicerr's own KSeF channel only ever authenticates with a token — its connection form has no certificate upload at all, so a qualified electronic signature / authorisation certificate (an option KSeF itself offers for other integrations) is not something you can use here.

  1. Log in to the Polish e-Tax portal (podatki.gov.pl).
  2. Navigate to KSeF → Token management.
  3. Generate a new API token for invoice submission.
  4. Set the appropriate permissions (at minimum: invoice:send, invoice:read).
  5. Copy and store the token securely.

3. Configure the KSeF environment​

KSeF has two environments:

EnvironmentURLPurpose
Testhttps://ksef-test.mf.gov.plDevelopment and testing
Productionhttps://ksef.mf.gov.plLive invoice submission

Start with the Test environment, validate your integration, then switch to Production.

4. Connect Invoicerr to KSeF​

Once you have your credentials, configure the KSeF channel in Invoicerr:

  1. Go to Settings → E-invoicing. The screen shows legal channels on the left and, for the selected one, the operators that implement it on the right. For a Polish company, KSeF is the country's own legal channel; it carries a "Recommended for your country" badge, not yet a "Mandatory" one (see the note below on why).

  2. Select KSeF on the left, then find KSeF (Krajowy System e-Faktur), the direct operator and Poland's own platform, in the operator list on the right and click Connect:

    The KSeF legal channel, with the KSeF operator to connect

  3. In the side sheet that opens, fill in the two fields this channel actually asks for:

    • NIP — your Polish tax ID
    • KSeF token — the API token from step 2 above
    • Environment — TEST or PRODUCTION (the same selector every channel offers)

  4. Click Connect at the bottom of the side sheet.

Why "Recommended", not "Mandatory"

KSeF is already the law (art. 106ga of the Polish VAT act): large taxpayers (over 200,000,000 PLN in 2024 sales) have been bound since 1 February 2026, and every other business since 1 April 2026. But the law also keeps a standing exception until 31 December 2026: a taxpayer may still issue an ordinary invoice for a given month as long as that month's KSeF-eligible sales stay at or under 10,000 PLN. Invoicerr's own mandate check compares a single date against an invoice's issue date; it cannot also weigh a rolling monthly sales total, so marking KSeF "Mandatory" today would block some invoices that are still genuinely lawful. The badge stays "Recommended" until the exception itself expires, which is a deliberate, sourced choice, not a gap in Poland's own data file.

Invoicerr will use these credentials to authenticate with the KSeF API and transmit invoices on your behalf.

Additional resources​