Invoicing in Poland, KSeF and the UPO, the ryczałt and the JPK files — written out step by step.
The National e-Invoicing System affects small service providers, but not all sales must be sent to KSeF. Receipts for individual clients remain outside the system, and a transitional limit of 10 000 zł gross applies to B2B invoices until the end of 2026. Learn how to manage your cost and sales invoices.
ФОП (FOP, Ukrainian sole trader) is not the same as JDG, Дія (Diia) will not open a Polish government portal for you, and KSeF is not ЄРПН. Here is a map of the terms that matter, plus what mandatory e-invoicing changes.
Excel and KSeF (Poland's National e-Invoice System) do not meet in the middle. KSeF accepts only XML files that match the FA(3) logical structure, validates them automatically, and issues a KSeF number plus a UPO receipt only after acceptance. A spreadsheet cannot build that structure, cannot guarantee unique sequential numbering when two people edit the same file, and cannot hold the document state after submission. Below: exactly where Excel breaks, and where it is still perfectly fine.
An invoice in KSeF (Poland's national e-invoicing system) cannot be edited, deleted or cancelled. Once it receives a KSeF number, the only remedy is a correction invoice issued by the seller. The buyer-side correction note was abolished on 1 February 2026 when Article 106k of the Polish VAT Act was repealed. A correction must reference the original invoice inside the DaneFaKorygowanej node, and the TypKorekty field states the moment at which it takes effect in the VAT records. Below: the required FA(3) fields, three ways to present the change at line level, and five situations where mistakes are most common.
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 delivers it through the in-app bell and browser push, with one switch for each of the five invoice event groups. Email and separate per-channel switches exist only for KSeF, certificate and tax declaration events. 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. Under the current act, financial penalties start the same day (the Ministry of Finance has announced a move to 2028, a bill not yet passed). 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 (the smallest ones from 1 January 2027; 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 other taxpayers from 1 April 2026 (the smallest from 1 January 2027; ksef.podatki.gov.pl). Under the current act, penalties under Article 106ni of the VAT Act apply from 1 January 2027. On 16 September 2026 the Ministry of Finance announced it will move them to 1 January 2028; that is a bill not yet passed, and it moves only the penalties, not the obligation to use KSeF. 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.
Under the current rules KSeF tokens (authentication keys for Poland's national e-invoicing system) expire on 31 December 2026. At consultations on 9 June 2026 the Ministry of Finance proposed keeping them, but no regulation has been adopted yet, so moving to a KSeF certificate is the safer choice. The June 2026 proposal of Poland's Ministry of Finance (MF) could change the practical answer to "how long," but for now 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. Logging in to KSeF with mObywatel, Poland's official government identity app, has been possible since 14 February 2026, when KSeF was integrated with the National Node of Electronic Identification. And because a new wave of companies fell under the obligation in April 2026 (the smallest ones from 1 January 2027), more people now log in manually, which makes the phone question a real one.
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