How to access the National e-Invoice System (KSEF) for companies in Poland?

With the implementation of the National e-Invoice System (KSEF), all capital companies, such as limited liability companies, joint-stock companies, and limited joint-stock partnerships, must prepare for the mandatory use of this system. The new schedule introduces obligations in stages:

- from February 1, 2026 for large entrepreneurs whose sales value (including tax) exceeded PLN 200 million in 2024, and

- from April 1, 2026 for other active VAT taxpayers.

From these dates, KSEF will become the only way to issue and receive structured invoices for the affected entities. The process of gaining access is simple but requires several formal steps, including registration with the tax office. In this article from our knowledge base, we explain how to do it step by step. If you need support, our team is available – contact us!

What is KSEF and why is it important for your company?

KSEF is a central system of the Ministry of Finance that automates invoicing processes, increases transaction security, and facilitates VAT settlements. For companies, this means the obligation to send and receive e-invoices in XML format directly to the system. The benefits? Faster settlements, reduced risk of errors, and full digitization of accounting. Lack of access after the deadline (February 1 or April 1, 2026, depending on the size of the company) may result in administrative penalties. We recommend starting preparations now to avoid the rush before the deadlines.

Prerequisites before gaining access

Before you start the process, make sure your company meets the basic requirements:

Possessing the company's NIP: This is the basic identification in the system.
Qualified electronic seal: Recommended for companies – it must be issued for the company's NIP and used to sign documents. Cost: about PLN 300–500 per year (depending on the provider, e.g., EuroCert).
Trusted Profile or ePUAP: Useful for logging in, but for companies, it is not always sufficient on its own.
Authorized person: President, accountant, or another employee with power of attorney to represent the company.

Note: For sole proprietorships (JDG) and small companies, the process is simpler (without ZAW-FA), but for capital companies, the ZAW-FA form is crucial, especially if your company is subject to the obligation from February 1 or April 1, 2026.

Steps to gain access to KSEF – step by step guide

Here is a detailed action plan. The entire process usually takes 7–14 days, depending on the tax office. Keep in mind the approaching deadlines: February 1, 2026, for large companies and April 1, 2026, for smaller ones – submit your application in advance.

Step 1: Obtain a qualified electronic seal

Select a certified provider (e.g., EuroCert, Certum, or Asseco).
Order the seal for the company's NIP – the process is online, with identity verification (e.g., video verification).
Once you have the seal, install the software to manage it (e.g., Adobe Sign or a dedicated tool from the provider).

Step 2: Fill out and submit the ZAW-FA form

Download the ZAW-FA form from the Ministry of Finance website (available on gov.pl).
Fill in the company details: NIP, REGON, name, address, and details of the person authorized for KSEF (first name, last name, PESEL, email).
Submit the form to the appropriate tax office:
Electronically: Via ePUAP or the Tax Portal (use the Trusted Profile).
In paper form: In person or by mail.
The office will confirm the application within 3–7 working days. You will receive an access reference number.

Tip: If the company already has access through the Trusted Profile, ZAW-FA extends it with the electronic seal. This is especially important for companies approaching deadlines in February or April 2026.

Step 3: Log in to the KSEF Taxpayer Application

Go to the website ksef.podatki.gov.pl.
Click "KSeF Taxpayer Application – log in".
Enter the company's NIP and choose a method of authentication:
- Trusted Profile (ePUAP) – free and fast, but limited to read-only access, ideal for testing and smaller companies.
- Qualified signature or electronic seal – provides full access and security, recommended for capital companies.
- KSeF certificate (if obtained) – dedicated to the system, requires ZAW-FA and is best for large companies with IT integration.
After the first login, the system will assign the company a unique identifier.

Step 4: Grant user permissions

In the KSEF panel, go to the "Permissions" section.
Add users (e.g., an accountant from the accounting office): provide their NIP/PESEL, email, and scope of rights (issuing, receiving invoices).
Sign the authorization with the company seal.
The user will receive an email with a link to accept.

How to receive and issue invoices in KSEF?

After gaining access:

Issuing: Use XML structure (ready templates on the KSEF site) and send via API or web interface.
Receiving: Invoices automatically go to the KSEF mailbox – download them in JPK_FA format.
Integration with accounting systems (e.g., Comarch, Sage): Possible through API, which facilitates our office work. From February 1 and April 1, 2026, these processes will become mandatory for the respective covered companies.

Common mistakes and tips

Error No. 1: Lack of a seal on the company's NIP – remember that a personal seal is not sufficient.
Error No. 2: Delay with ZAW-FA – submit it as soon as possible, even if KSEF is not yet mandatory; the deadlines of February 1 and April 1, 2026, are approaching quickly.
Test the system: Right after gaining access, try sending test invoices in sandbox mode.
Security: Only use official gov.pl sites to avoid phishing.

How can we help you at the accounting office?

Our office offers full assistance: from preparing ZAW-FA, to obtaining the seal, to integrating KSEF with your accounting. Contact us to schedule a free consultation. Together, we will ensure that your company is ready for the deadlines of February 1 and April 1, 2026, and the e-invoicing revolution!

Sources: Official guidelines from the Ministry of Finance and gov.pl portals.