As of February 1, 2026, many companies will be required to issue structured invoices through the National e-Invoice System. Implementing the KSeF system in your company presents many challenges, one of which is the authorization process using KSeF certificates. Learn what a KSeF certificate is and what it's used for, how to obtain one, and what to do when it expires.
What exactly is the KSeF certificate needed for?
According to information published by the Ministry of Finance and the specifications of the National e-Invoice System (KSeF), the KSeF certificate is intended to serve as one of the authentication methods in the KSeF system. The aforementioned KSeF is an IT system used to issue structured invoices, also known as electronic e-Invoices.
Use of this solution will soon become mandatory – from February 1, 2026, this obligation will apply to businesses whose sales, including taxable amount, exceed PLN 200 million in 2024, and from April 1, 2026, to other businesses (with certain exceptions). Work is currently underway to create version 2.0 of the KSeF system, and its additional functionalities (such as the ability to obtain a KSeF certificate) will become available to taxpayers in the coming months.
The KSeF system has already had one release – version 1.0, which taxpayers can now use voluntarily. Use of this version was initially intended to be mandatory, but due to numerous skeptical voices from businesses and professionals, as well as technical issues, the effective date of this requirement was postponed. This version will cease to be available once the new production environment is launched. What is the significance of the KSeF certificate in all of this?
In the new system architecture (version 2.0), KSeF certificates will replace the authentication tokens previously used in version 1.0 of the KSeF system. These solutions are intended to operate in parallel for a period of time – until December 31, 2026. It's also worth noting that the KSeF token and the KSeF invoice issuer certificate are not functionally equivalent. The KSeF certificate is intended to authenticate the taxpayer and enable them, among other things, to access the new KSeF API or issue a structured invoice if access to the KSeF system is unavailable.
How to get the KSeF certificate step by step
The target KSeF certificates are not yet available – the Ministry of Finance informs on its website that taxpayers will be able to apply for them from November 1, 2025. On that day, the KSeF Certificates and Authorizations Module (MCU) will be launched, where it will be possible to grant authorizations to KSeF users, apply for certificates and download them.
To obtain KSeF certification through MCU, you must take the following steps:
- Authenticate yourself in KSeF – this will be possible, among others, through a qualified electronic seal and a trusted signature
- Apply for a KSeF certificate – it will be necessary to provide the details of the entity or individual that were authenticated in the previous step
- Download the KSeF certificate – once your application has been processed, the KSeF certificate will be ready for download
The Ministry has also planned a series of training sessions across Poland from September to December. One of the topics discussed will be the process of obtaining and downloading certificates. Therefore, it's worth following announcements on the Ministry of Finance website or inquiring about the next training session at your local tax office.
A separate issue is the test certificates required to test the KSeF 2.0 API functionality. According to government announcements, integration teams tasked with implementing KSeF in company software will have access to the KSeF 2.0 test environment from September 30, 2025 – developers will likely be able to generate a KSeF test certificate at that time. However, it is already available KSeF API documentation – both official and those concerning alternative commercial solutions (such as e.g. KSeF API), which significantly facilitate the implementation of KSeF in the company.
What is the KSeF invoice issuer certificate used for?
A KSeF invoice issuer certificate will be required to perform at least several activities. Two key ones are access to the KSeF 2.0 API and authentication of entity data (sole proprietorships or partnerships). It will therefore be a tool enabling the unambiguous identification of the user. At the same time, this solution allows you to confirm the identity of the invoice issuer.
Already during the design phase of the National e-Invoice System, the Ministry of Finance identified various threats. One of these is the temporary unavailability of the KSeF system, which could be caused by a failure, for example. To ensure that such a situation doesn't deprive businesses of the ability to issue invoices, a solution has been provided: offline invoice generation. However, this will also require the use of a KSeF certificate – it will be necessary for issuing invoices during periods of KSeF system unavailability.
Many Polish companies collaborate with foreign contractors who won't be using the KSeF system. Hence, another function of the KSeF certificate is that it will be required to generate a QR code, which will then be forwarded along with the invoice to the contractor outside the KSeF system. The system designers intended this solution to ensure an adequate level of security – the QR code is intended to confirm the invoice's authenticity.
What should I do when my KSeF certificate expires?
In published materials, the Ministry of Finance announced that KSeF certificates will have a limited validity period – they are to be issued for a period of two years. The procedure after a certificate expires is reduced to repeating the steps required to obtain it. Therefore, it is necessary to re-authenticate in the KSeF MCU module, apply for the certificate, and download it.
This is the status as of the end of August 2025 – this procedure may change in the future. Information on many details of the KSeF system's operation and procedures in various situations is not yet available. Therefore, it is expected that in the coming months the Ministry of Finance will issue further announcements clarifying specific procedures – including what to do after a KSeF certificate expires and how to obtain another certificate.
