®Poland KSeF e-invoicing integration
Poland's National e-Invoicing System (KSeF) is mandatory. Invoices are issued through a central government platform in a defined XML schema, and your software has to connect to the KSeF API. We integrate your ERP or billing system with KSeF so invoices are issued, received, and archived correctly.
Prefer to write? Email sales@nowgray.com with the software you run today and your timeline.
Large taxpayers (2024 turnover above PLN 200 million) were brought in from 1 February 2026, and most other VAT-registered businesses from 1 April 2026, with a penalty grace period into the end of 2026.
- KSeF API integration
- FA structured XML schema
- Authentication & tokens
- Issue, receive & archive
What is KSeF (Krajowy System e-Faktur) in Poland?
KSeF (Krajowy System e-Faktur) is Poland's National e-Invoicing System, a central government platform through which structured invoices are issued and received. Unlike the Peppol model used by some countries, KSeF is a clearance system: your invoice is sent to KSeF, which assigns it an identifier, and that is the legally issued invoice.
Invoices use a defined XML schema (the FA structured invoice format), and your software authenticates to the KSeF API with tokens or qualified signatures. Large taxpayers (2024 turnover above PLN 200 million) were brought in from 1 February 2026, and most other VAT-registered businesses from 1 April 2026. A penalty grace period runs into the end of 2026, and some elements such as the KSeF number in payments were deferred.
We handle the KSeF API connection, the schema mapping, authentication, and archiving so your invoicing keeps working through the transition.
A complete Poland integration.
Whether you run an off-the-shelf ERP, a cloud accounting app, or a POS you built in-house, we make it comply with KSeF (Krajowy System e-Faktur), end to end.
KSeF API integration
We connect your software to the KSeF API for issuing, receiving, and retrieving invoices.
FA XML schema mapping
We map your invoice data to the required FA structured XML schema so documents are accepted.
Authentication & tokens
We set up KSeF authentication with tokens or qualified signatures and manage credentials securely.
KSeF identifier handling
Each issued invoice receives its KSeF identifier, tracked back into your system as the proof of issue.
Receiving & archiving
Inbound invoices are retrieved from KSeF and archived in line with the retention rules.
ERP / billing integration
All of this runs inside your existing ERP or billing software, so your team's workflow does not change.
The Poland compliance timeline.
Starting before enforcement means a calm cutover. Waiting means doing it under pressure.
Large taxpayers
Businesses with 2024 turnover above PLN 200 million were brought into mandatory KSeF.
Other VAT businesses
Most other VAT-registered businesses came into scope.
Grace period
A penalty grace period runs into the end of 2026, and some elements were deferred. Confirm the current status with the Ministry of Finance.
Who the KSeF (Krajowy System e-Faktur) rules affect.
Large taxpayers
Businesses with 2024 turnover above PLN 200 million were brought into mandatory KSeF from 1 February 2026.
Other VAT-registered businesses
Most other VAT-registered businesses came into scope from 1 April 2026, with micro-businesses following.
ERP and accounting users
Any business whose ERP or accounting software has to issue and receive invoices through the KSeF API.
Dates and thresholds change, and scope depends on your exact situation. Treat this page as a starting point, confirm the detail with the Polish Ministry of Finance, and tell us what you run today, we will tell you plainly what an integration would involve.
Built into the software you already run.
We integrate KSeF into your existing ERP or billing software: the API connection, the FA XML schema, authentication, identifier handling, and archiving. If you run a system that cannot connect to KSeF, we build or adapt one that can.
KSeF is a clearance model, so the KSeF identifier is what makes your invoice legally issued. We make sure that flow is reliable.
Poland e-invoicing questions.
Is KSeF mandatory?
Yes. Large taxpayers (2024 turnover above PLN 200 million) were brought in from 1 February 2026 and most other VAT-registered businesses from 1 April 2026, with a penalty grace period into the end of 2026. Confirm the current dates with the Polish Ministry of Finance.
How is KSeF different from Peppol e-invoicing?
KSeF is a central clearance system: your invoice is sent to the government platform, which assigns an identifier, and that is the legally issued invoice. We integrate your software with the KSeF API directly.
What format do KSeF invoices use?
A defined FA structured XML schema. We map your existing invoice data to it so documents are accepted on submission.
Can you integrate KSeF with my ERP?
Yes. We connect your existing ERP or billing software to the KSeF API, including authentication, identifier handling, and archiving. We also build compliant systems.
How do I get started?
Email sales@nowgray.com with your ERP or billing software and your turnover tier. We will scope the KSeF integration.
Start your Poland e-invoicing integration.
Tell us what software you run and your timeline. We will scope the integration and get you compliant with KSeF (Krajowy System e-Faktur) well before enforcement reaches you.
Enquiries: sales@nowgray.com · Source of truth: Polish Ministry of Finance