The National e-Invoice System (KSeF) is no longer just a technological concept but has become a binding legal reality. This change redefines how we understand the issuance of sales documents—an invoice is no longer a PDF file sent via email, but a structured set of digital data in XML format. However, before your company sends its first document to the Ministry’s system, it must go through a crucial step: successful authentication. This is the process of verifying identity, which serves as the digital key to the Ministry of Finance’s gates. Without it, the system will not recognize your authorization to operate under a specific NIP (Tax Identification Number).
Depending on whether:
Your path to KSeF will be different. We’ve put together a guide for you—a sort of “roadmap” for logging in.
The most common questions we receive are: How do I create a user account on KSeF?
Good news—you don't need to set up an account. It's already there (linked to your tax ID number); you just need to prove that you're authorized to use it.
Individual (not engaged in business activity) / Sole Proprietorship
This is the simplest case. You are the “rudder, the sailor, and the ship.”
Method: You authenticate yourself as “yourself.”
Tools: a free Trusted Profile or a Qualified Electronic Signature (QES).
How it works: You log in directly. The system recognizes your PESEL number linked to the company’s NIP.
Commercial Law Entities (LLCs, Corporations, Limited Partnerships, General Partnerships) Here we enter the world of “entities that are not natural persons.” A company has no hands to sign its name, nor does it have a personal identification number (PESEL). Instead, it has a tax identification number (NIP).
Method – recommended option: Qualified Electronic Seal. This is a digital version of a company stamp. It allows for the automation of processes and makes them independent of any specific individual (e.g., the CEO, who may be on vacation).
Traditional option: Submit a ZAW-FA form to the Tax Office. In the form, you designate a specific person (e.g., the CEO) who will use their personal signature to log in on behalf of the company.
“Third sector” entities and others (associations, foundations, cooperatives, housing communities).
The rule is similar to that for companies. People often ask: Is KSeF mandatory for all businesses? Yes, it is also mandatory for active VAT taxpayers in these groups.
Procedure: If an entity has a tax identification number (NIP), it may obtain an electronic seal.
Alternative: If the management board consists of multiple members or you do not wish to invest in a company seal, you must submit a ZAW-FA form to authorize an individual (e.g., a property manager or the association’s treasurer) to log in.
Local Government Units (Local Government Units – Municipalities, Counties) – a vast topic: the municipality, as a “super-taxpayer,” oversees schools and preschools (budgetary units).
Main Office: Authentication is performed using a qualified digital certificate or by designating a person (Village Administrator/Mayor) via ZAW-FA.
Subordinate units: they are granted authority “from above” by the main unit or exercise authority within a hierarchical structure.
An electronic seal is the digital equivalent of a company stamp. It enables ERP systems to send invoices in bulk automatically without requiring employees to sign each one. It ensures independence from personnel changes and the highest level of data security.
Automation
Financial and accounting systems require digital signatures to "sign off" on bulk mailings without human intervention or requiring the accountant to click each time.
Security and Integrity:
The seal guarantees that the document originates from a specific company and has not been altered since it was issued.
Independence
Employees may leave the company, but the stamp assigned to the organization’s tax identification number (NIP) remains, ensuring business continuity without the need to submit new ZAW-FA forms every time there is a personnel change.
The Ministry of Finance has prepared contingency plans. If the system is unavailable, an invoice with a QR code (Quick Response—a graphic code that allows for quick data reading) may be issued; this invoice must be uploaded to the system within one business day after the outage has been resolved.
Please note, however, that a KSeF Type 2 Certificate is required to generate codes verifying the issuer’s identity in OFFLINE mode.
KSeF isn’t just a new tax requirement—it’s a digital leap forward for your business. The key to navigating this revolution smoothly is choosing the right digital identity.
Whether you run a small sole proprietorship or manage a large corporation, make sure you have a signature or seal ready today. Don’t wait until the last minute or for a system failure on the deadline.
If you need help obtaining a qualified digital seal or digital signature, check out the services available at podpisano.pl.
For more information on KSeF procedures, visit the official website ksef.podatki.gov.pl and in our knowledge base.
This article was prepared based on the KSeF 2.0 Handbook (Ministry of Finance, September 2025) and information from the website ksef.podatki.gov.pl.
