The National e-Invoicing System (KSeF) is a revolution that is changing the way companies issue and receive invoices. For companies and large organizations, the process of „entering” the system may seem complicated, but there is a shortcut. If your organization has a qualified electronic seal, you can bypass office visits and paperwork.
At podpisano.pl we value simple solutions, so we have prepared step-by-step instructions on how to register (authenticate) with the system using the seal.
Nowadays, in the digital world, a qualified electronic seal is the equivalent of a company stamp and representative signature, but in a virtual version. The key difference between it and a personal signature is that the seal contains the data of the entity (company), including the NIP number.
This allows the KSeF system to automatically recognize the company. You do not need to file a paper notice ZAW-FA at the tax office, to designate the first person authorized to the system. You simply „enter” the system with a seal and immediately gain full ownership rights.
Before you go clicking, see the flowchart. The whole process is based on the „challenge-response” principle. The system throws a digital challenge (a file to sign), and you send it back sealed.
This process is technically called „authentication„. Here's what you need to do, based on the official instructions of the Ministry of Finance.
Entering the application Launch your browser (recommended: Chrome, Firefox, Edge or Safari) and go to the Taxpayer Application KSeF page.
To log in to KSeF go to https://ap.ksef.mf.gov.pl/web/
Preparation Make sure you have a device or app on hand to fold stamps qualified and installed software provided by the issuer of your seal. W podpisano.pl Seamlessly produce a qualified electronic seal without queues and stress.
Select how to log in → Log in with a qualified certificate.
Identification In the login window, enter the number NIP your company. The system will ask for the login context - make sure you enter NIP of the entity you want to log in. Click the Authenticate.
Authentication request (AuthRequest) This is the most important moment.
Affixing the seal
Uploading to KSeF
Done! If the verification is successful, you will see the application's startup dashboard.
In a situation where the authorization is successful, an informational message will be displayed containing the session number.
It is possible to copy the session number by clicking [1] „Copy”. The session number is necessary when verifying the status of invoice shipment in a given session.
Click the [2] „OK” button to close the window.
Attention! Assuming that the file has been signed correctly, clicking the „Next” button will take us to the Application with authorization for the NIPu context we selected at the beginning.
Note that authorization using a signature with NIPem other than NIPem context, or a signature with PESELem requires prior authorization for these identifiers.
Once you're in as „owner” (super-administrator), your goal is not to invoice daily using this method (it's too cumbersome), but to set up your business.
Once you have authenticated in the Taxpayer KSeF Application, you will be presented with a screen to enter the invoice and the main Menu of the application. REMEMBER after the first login:
Using an electronic seal is the fastest way to „activate” a company in KSeF. You bypass visits to the office, and the whole process takes a few minutes in front of your computer.
Remember, however, that the seal is mainly for opening doors and management - it's a good idea to authorize specific employees or IT systems for day-to-day work.
If you need help getting a qualified electronic seal, check out the offer on podpisano.pl.
You are also welcome to contact podpisano.pl - We will help you secure your company's digital identity.
For more information about KSeF procedures, visit the official website ksef.podatki.gov.pl And in our knowledge base.
The article is based on Handbook KSeF 2.0 (MF, September 2025) and information from ksef.podatki.gov.pl.
