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Most KSeF software comparisons stop at the pricing page and a feature list. That is not enough. Below are eight questions that actually separate the tools: FA(3) schema support, authentication method, behaviour during a KSeF outage, purchase invoice retrieval, error readability, team permissions, data export, and what the subscription really covers. Ask them during the demo, not after rollout.
Biurko records every event on an invoice (issued, emailed, delivered, opened by the client, marked paid, KSeF response) and pushes it to you through three channels: the in-app bell, browser push notifications, and email. Every event group and every channel toggles independently. What Biurko does not do: it has no bank connection, so "paid" is a status you or your accountant set, not something the system detects.
KSeF downtime and a Profil Zaufany outage are two separate events with very different legal consequences. Poland's Ministry of Finance publishes KSeF notices on ksef.podatki.gov.pl and in its Public Information Bulletin (BIP); Profil Zaufany announcements live on gov.pl/web/profilzaufany. Live API availability is on biurko.io/ksef/status. Your deadline to upload a held invoice depends on which mode formally applies: one business day or seven.
On 1 February 2026 the FA(3) schema replaced FA(2) and the production 1.0 API stopped working. This was a new integration contract, not an upgrade. Main API changes: JWT authentication decoupled from sessions, mandatory encryption of every invoice, KSeF certificates, per-invoice batch processing, new duplicate detection, new permission model. Main schema changes: an attachment node, a new "Employee" party role, the 0% rate and the NP code split into specific codes, flexible payment terms, IBAN up to 34 characters. The consequences are commercial, not only technical: invoice numbering, VAT rate mapping, and who in your accounting team can actually see a client's invoices.
If you run a small business in Poland, you may have heard reassuring news: as long as your invoices stay under PLN 10,000 a month, you can keep issuing them the old way. That is true, but only until 31 December 2026. This limit is not a permanent break. It is a transitional rule built to expire. Why it matters now: from 1 January 2027, the obligation to issue invoices through KSeF (Poland's National e-Invoicing System) applies to everyone, regardless of turnover. Financial penalties start the same day. If you are planning your 2027 operations around this limit, it is worth checking what the law actually says and whether the Ministry of Finance intends to extend anything.
You log in to KSeF (Poland's national e-invoicing system) with Profil Zaufany (Poland's free Trusted Profile), and one morning the system tells you it has expired. Since 1 April 2026, issuing invoices through KSeF is mandatory for most businesses, including sole proprietors (KSeF rollout plan, gov.pl), so this is not something to "get to later." Without a valid Profil Zaufany you can't log in through the Węzeł krajowy (the national identity gateway) and you can't generate a KSeF certificate. Invoices pile up, and a client is waiting. The good news: in most cases you recover access in minutes. The catch: if the profile has already expired, the path is different from a simple renewal.
Here is a habit I keep running into when companies switch to Poland's mandatory e-invoicing: to let the accountant "handle KSeF," someone hands over the login to the owner's Profil Zaufany (Poland's Trusted Profile, the state e-identity used to sign in to public services). Convenient for five minutes, risky for a year. That login is your identity across the whole tax and public administration, not just invoices, and Poland's Ministry of Finance treats sharing it as unacceptable. The good news: you do not need to. KSeF (Poland's National e-Invoicing System) has a built-in permission model. Your accountant gets their own named access and signs in with their own Profil Zaufany, and you can revoke it at any time.
Before you issue your first invoice through KSeF (Krajowy System e-Faktur, Poland's national e-invoicing system), you have to prove who you are. That sounds trivial, but it's where most people get stuck. KSeF 2.0 offers five different authentication methods, each works differently, and each suits a different type of user. This matters now because KSeF is already mandatory. It applied to the largest taxpayers from 1 February 2026 and to all active VAT payers from 1 April 2026 (ksef.podatki.gov.pl). 2026 was a penalty-free grace period, but from 1 January 2027 the tax office can impose sanctions. Choosing a login method isn't paperwork. It's the precondition for issuing invoices at all.
You run a small business in Poland. Some of your sales go to companies, some to ordinary consumers. You have heard about the 10,000 PLN limit that lets the smallest sellers stay outside KSeF (Poland's national e-invoicing system) a little longer. And the obvious question follows: do you add both types of sales together, or only one? This is not a theoretical detail. From 1 April 2026 the obligation to issue invoices through KSeF applies to most VAT payers, but the smallest businesses received a deferral until 31 December 2026, based on this monthly 10,000 PLN limit. From 1 January 2027 the obligation covers everyone. And crossing the threshold even once is irreversible. So it pays to calculate the limit exactly the way the Ministry of Finance calculates it.
Until spring 2026 the answer was simple. A KSeF token (an authentication key for Poland's national e-invoicing system) worked through 31 December 2026, and from 1 January 2027 only certificates would remain. That certainty no longer holds. On 9 June 2026 Poland's Ministry of Finance (MF) announced that tokens will stay in the system permanently. That changes the practical answer to "how long," but not one detail: it is still a proposal, not a rule. If your accounting software logs into KSeF with a token, you need to know what is already settled and what is not yet in law.
"Is there a KSeF app for my phone?" is one of the most common questions from business owners since KSeF (Poland's national e-invoicing system) became mandatory. The short answer is a little surprising: yes to the phone, no to issuing invoices from it. Since February 2026, the Ministry has allowed logging in to KSeF with mObywatel, Poland's official government identity app. And because a new wave of companies fell under the obligation in April 2026, far more people now log in manually, which makes the phone question a real one.
The first login to KSeF (Poland's mandatory national e-invoicing system) trips up more people than issuing the actual invoice. The Taxpayer Application shows several authentication methods, and none of them explains which one is right for you. This is not a trivial choice. Since 1 February 2026, KSeF has been mandatory for the largest companies, and since 1 April 2026 for all other businesses (Ministry of Finance timeline). Without valid authentication you can neither issue nor receive a structured invoice.
You enter the company NIP (Polish tax ID), pick Profil Zaufany (Poland's Trusted Profile e-identity), confirm through your bank, and instead of the KSeF dashboard you get an error or bounce back to the start page. Since the launch of KSeF 2.0 (Poland's mandatory national e-invoicing system), this is one of the most reported problems. The good news: it is rarely a fault with your company or a „wrong NIP”. Usually the cause is an expired profile, a data mismatch in the business register, missing permissions for the right entity, or plain browser cache. Each of these has recognisable symptoms and a fix you can apply yourself. Below are the 7 most common reasons Profil Zaufany login to KSeF fails, with concrete steps for each. This matters now, because KSeF is mandatory from 1 February 2026 for the largest companies and from 1 April 2026 for everyone else, and a blocked login means blocked invoicing.
issuing your first invoice in KSeF (Poland's National e-Invoicing System) comes down to three things: authenticating, filling in data that matches the FA(3) structure, and submitting. The system then assigns a KSeF number and returns a UPO (official receipt confirmation). Everything else is detail you can learn in a coffee break.
On 9 June 2026 Poland's Ministry of Finance proposed keeping tokens as a permanent login method for KSeF, including after 31 December 2026. This is a consultation proposal, not law. Even if adopted, tokens get a validity window of 1 to 365 days, and offline invoicing still requires a certificate. The migration is not cancelled. Only its deadline moved.
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