KSeF — Poland's national e-invoicing system — is no longer optional. The obligation to issue structured invoices went live on 1 February 2026 for the largest companies and 1 April 2026 for everyone else. For most business owners, the first real obstacle isn't the invoicing itself. It's the login screen.
Here's the good news. If you run a JDG (jednoosobowa działalność gospodarcza — a Polish sole proprietorship), you don't need an expensive qualified signature or a company seal. You need one free tool that you may already have: a Profil Zaufany (Trusted Profile).
This guide walks you through logging in to KSeF with a Profil Zaufany — what you need, where to click, and what you'll see on the other side. No jargon, under five minutes. And it matters now: the penalty-free grace period runs only until 31 December 2026, with sanctions starting 1 January 2027.
What Profil Zaufany is, and why it's enough for a sole trader
A Profil Zaufany (Trusted Profile) is Poland's free, government-issued way to prove your identity online — the same credential you'd use to file with social security or apply for an ID card. KSeF accepts it as a full authentication method.
For a sole proprietorship, this is as simple as it gets. Because you, as an individual, are legally entitled to act for your own business, the system grants you owner permissions automatically, based on your NIP (Polish tax ID). No application, no ZAW-FA form, no waiting for the tax office.
That's the key difference from companies. A limited company must first designate an owner — using a qualified seal or a paper ZAW-FA notification to the tax office. A JDG skips that step entirely.
What you need before you log in
Before you reach the login screen, check four things:
An active Profil Zaufany — set up through your bank or confirmed at a government point. If you don't have one, online banking is the fastest route.
Your company NIP — you log in as a taxpayer using this, not your PESEL (personal ID number).
Your phone or banking app — to confirm the operation (SMS code or in-app approval).
A browser — ideally a current version of Chrome, Firefox, or Edge.
That's all. No card reader, no software install — those are requirements for a qualified signature, not for a Profil Zaufany.
Logging in to KSeF, step by step
Go to the official site ksef.podatki.gov.pl and select "Aplikacja Podatnika KSeF 2.0" (the Taxpayer Application). You can also go straight to ap.ksef.mf.gov.pl. Always check that the address ends in
mf.gov.pl.Click "Przejdź do Aplikacji Podatnika KSeF 2.0" (Go to the Taxpayer Application), then on the login page click "Uwierzytelnij się w Krajowym Systemie e-Faktur" (Authenticate in KSeF).
Tick the declaration checkbox and click "Przejdź dalej" (Continue).
Choose an identification method → "Zaloguj profilem zaufanym" (Log in with Trusted Profile). This option also covers the e-Dowód (e-ID card) and online banking login.
Enter your company NIP.
Confirm your identity. The system redirects you to login.gov.pl. Sign in through your banking app, or with your Profil Zaufany username and password.
Sign the operation — with an SMS code or an approval in your banking app.
You're returned to KSeF automatically. Your NIP appears in the top-right corner. You're in.
With a working Profil Zaufany, the whole thing takes two to three minutes.
What you'll see after logging in
The main panel is simpler than you'd expect. Your company NIP sits in the top-right corner (worth a quick glance to confirm the data is right), and a menu on the left holds the core functions:
Issue and upload invoices — create an invoice manually or upload an XML file.
Invoice list — sales and purchase invoices pulled from the system.
Permissions (Uprawnienia) — grant access to your accountant, an employee, or an accounting office (by NIP or PESEL).
Tokens and certificates — the keys that connect KSeF to your invoicing software.
This is enough to issue your first invoice by hand or download a document from a supplier. But if you issue more than a handful a month, you'll quickly hit the limits of the government app — more on that below.
Watch out for scams: how to spot the real login screen
Fake "invoice" emails and spoofed login pages have appeared around KSeF. Three rules protect you in every case:
The real address ends in
mf.gov.pl(ap.ksef.mf.gov.pl). Don't log in via email links — type the address by hand.KSeF never asks for your Profil Zaufany password on its own page. It redirects you to the official login.gov.pl, and only there do you enter credentials.
The Ministry doesn't email invoices. Invoices land inside KSeF, not your inbox. An "invoice.pdf" attachment in an email is a classic scam signal.
If login fails before you panic: clear your browser cache, try a different browser, or wait a few minutes — government services have occasional outages. KSeF helpline: +48 22 330 03 30 or 801 055 055.
Profil Zaufany isn't the whole story — when you need a certificate
Here's the catch few people state plainly. A Profil Zaufany is great for logging in manually in a browser. But you can't use it to connect KSeF to invoicing or accounting software — for that you need a token or a KSeF certificate.
The difference is practical. A certificate is your "digital proof of identity" that software stores and uses in the background. With it, your program sends and receives invoices automatically, without you logging in with a Profil Zaufany each time. A certificate is valid for two years and is the Ministry's intended long-term standard for integrations.
This is exactly where the government app runs out of road and real convenience begins. The Taxpayer Application won't notify you of a new invoice, won't pull purchases automatically, and won't warn you before a certificate expires. At a few dozen documents a month, that's work better handed to a tool.
KSeF login — quick checklist
I have an active Profil Zaufany (set up via bank or government point)
I know my company NIP — I log in with it as a taxpayer
I only visit addresses ending in
mf.gov.plI choose "Log in with Trusted Profile" and confirm identity on login.gov.pl
After logging in, I check the NIP in the top-right corner
I grant access to my accountant/office under "Permissions"
For daily invoicing, I generate a KSeF certificate and connect my software
In short
Logging in to KSeF with a Profil Zaufany is the simplest way in for any sole trader — no signature, no ZAW-FA, just a few minutes. But it's only the front door. For everyday work, the government app is clunky: it doesn't receive invoices automatically and won't track deadlines for you.
Biurko connects to KSeF through a certificate and does that work in the background — sending, receiving, and watching your certificate's expiry, while translating error messages into plain language. Try Biurko free for 14 days at biurko.io and stop logging in by hand for every invoice.
FAQ
Can I log in to KSeF without a qualified signature? Yes. If you run a JDG (sole proprietorship), a Profil Zaufany is enough — the system grants you owner permissions automatically once you log in with your NIP. A qualified signature or seal is mainly needed by companies for their first authentication.
Is logging in to KSeF with a Profil Zaufany free? Yes. Both the Profil Zaufany and access to the government KSeF Taxpayer Application are completely free. You only pay if you choose a commercial invoicing tool for convenience and automation.
Does KSeF login work on a phone? Yes. The Taxpayer Application runs in a mobile browser, and you confirm your identity conveniently through your banking app. This is often the fastest method — no passwords to retype.
What should I do if I can't log in to KSeF? First, clear your cache and cookies, or try a different browser. Check that you selected the correct profile (individual vs business). If the issue is on the system's side, wait a few minutes or call +48 22 330 03 30.
Is a Profil Zaufany enough to issue invoices from my accounting software? No. A Profil Zaufany is for manual login in a browser. To connect KSeF to invoicing software, you need a token or a KSeF certificate — the certificate (valid two years) provides a stable, automated integration.