The inFakt Alternative Question: Where Biurko.io Actually Fits

KSeF & e-invoices

Invoicing in Poland, KSeF and the UPO, the ryczałt and the JPK files — written out step by step.

How to Grant KSeF Permissions to Staff or an Accountant
KSeF & e-invoices
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How to Grant KSeF Permissions to Staff or an Accountant

If your Polish company is owned or run from abroad, the permissions question in KSeF (Poland's national e-invoicing system) usually comes down to one form you can't avoid: the ZAW-FA. A Polish sole trader can skip it. A foreign-owned limited company almost always cannot. This matters because KSeF is already mandatory — since 1 February 2026 for the largest taxpayers and since 1 April 2026 for most remaining VAT payers (the smallest from 1 January 2027). Under the current act, penalties under Article 106ni of the VAT Act apply from 1 January 2027 and reach up to 100% of the VAT shown on the invoice. 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. Getting access right for the people who actually issue and book your invoices is worth doing now, calmly. Below: who files ZAW-FA and when, how to designate your first user, and how to grant access to an employee or accounting office.

KSeF Environments: Where to Practice Without Breaking Anything
KSeF & e-invoices
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KSeF Environments: Where to Practice Without Breaking Anything

Picture this: you're training a new team member to issue invoices. They click "send" on a test invoice — and it lands in the production KSeF as a real document, complete with made-up data. Or the opposite happens: they practice in demo, everything works, but the invoices are nowhere to be found in the taxpayer app, because they're looking at a completely different environment. KSeF (Poland's national e-invoicing system, Krajowy System e-Faktur) has been mandatory since 1 February 2026 for the largest taxpayers and since 1 April 2026 for other taxpayers (the smallest from 1 January 2027). Under the current act, penalties under Article 106ni of the VAT Act apply from 1 January 2027, and on 16 September 2026 the Ministry of Finance announced it will move them to 1 January 2028; that is a bill not yet passed. Production invoices are already real accounting documents. So before anyone on your team starts clicking "send," it's worth knowing where you can safely practice. This article explains the three KSeF environments — test, demo and production — what each is for, and how not to mix them up.

KSeF is down — now what? offline24 mode, calmly explained
Invoicing in practice
1311

KSeF is down — now what? offline24 mode, calmly explained

When you can't send an invoice to KSeF (Poland's national e-invoicing system) — because your internet dropped, your software is lagging, or you simply can't log in — you don't have to stop selling. offline24 mode lets you issue the invoice outside the system and upload it by the next business day. Below we explain the difference between the four special modes (offline24, offline, emergency, and total outage), walk through offline24 step by step, list the common traps, and show what good software handles for you. No panic, no legal jargon.

FA(3) Schema: Which E-Invoice Fields Are Actually Mandatory
KSeF & e-invoices
27017

FA(3) Schema: Which E-Invoice Fields Are Actually Mandatory

The FA(3) schema has hundreds of fields, but only a fraction are truly mandatory. This article breaks the structure into three requirement levels, shows the four blocks KSeF rejects an invoice without, and warns about the "optional" fields the system will happily accept while a tax audit will not.

KSeF Number on an Invoice: What It Means, Where to Find It, Who Needs It
KSeF & e-invoices
27986

KSeF Number on an Invoice: What It Means, Where to Find It, Who Needs It

The KSeF number sounds like something printed on the invoice next to the invoice number. It isn't — the system assigns it once the file is accepted, and it appears on the PDF only if your software adds it there. That's one of the most common points of confusion since Poland's national e-invoicing system (KSeF) became mandatory — businesses hunt for the KSeF number on the PDF, or mix it up with their own numbering or with the reference number on the UPO (the system's official receipt confirmation). And it matters more every month. Since 1 February 2026 the KSeF number must be reported in JPK_V7 (Poland's combined VAT return and ledger file), on both the sales and purchase side. From 1 January 2027 it must appear in the title of every bank transfer between active VAT payers. This guide explains what the KSeF number actually is, how it's built, where to find it, and — most importantly — who needs it and when.

Will KSeF Deadlines Be Postponed Again? What's Actually Left
KSeF & e-invoices
27741

Will KSeF Deadlines Be Postponed Again? What's Actually Left

KSeF — Poland's mandatory national e-invoicing system — was delayed so many times that "I'll wait, they'll probably push it again" became a default strategy for a lot of companies. For a while it even paid off: the original July 2024 date really did slip. The catch is that the two dates that mattered most have already passed. Since 1 February 2026, large companies invoice through KSeF, and since 1 April 2026, so does essentially everyone else (the smallest taxpayers join on 1 January 2027). The system is live, it's mandatory, and no one is rolling it back. Anyone still waiting for "one more postponement" is waiting for something that, for the core obligation, isn't coming. The postponement the Ministry announced on 16 September 2026 concerns only the penalties, not the obligation itself. Below: what is genuinely still in play for 2026 and 2027, why betting on another delay is now the most expensive option, and how to set your business up so no date surprises you.

Fixed Establishment and KSeF: When Foreign Companies Must E-Invoice
KSeF & e-invoices
28197

Fixed Establishment and KSeF: When Foreign Companies Must E-Invoice

From 1 February 2026, Poland's largest taxpayers — and from 1 April 2026, the remaining taxpayers (the smallest from 1 January 2027) — must issue invoices through KSeF (Poland's national e-invoicing system). If your company is foreign-owned or foreign-headquartered, the first question is simpler than it looks: does this obligation apply to you at all? The answer doesn't turn on whether you hold a Polish NIP (tax ID) or who owns the company. It turns on whether you have a fixed establishment (FE) in Poland that takes part in your sales. On 28 January 2026, Poland's Ministry of Finance (MF) issued official tax guidance clarifying exactly when that obligation arises — and when it doesn't. Here's where the line falls, and what it means for you and your Polish trading partners.

KSeF Calendar 2026/2027 — Every Deadline You Need to Keep Track Of
KSeF & e-invoices
28724

KSeF Calendar 2026/2027 — Every Deadline You Need to Keep Track Of

KSeF (Poland's national e-invoicing system, run by the Ministry of Finance) had its rollout pushed back so many times that most business owners are still working from a version that's two amendments out of date. The current reality is concrete: since 1 February 2026, receiving e-invoices through KSeF is mandatory for everyone, and the obligation to issue them reached most of the market on 1 April 2026. The rules are live, but administrative penalties aren't being applied yet. 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 — a bill not yet passed, which moves only the penalties. From 1 January 2027 the smallest companies join the system, and under the current rules KSeF tokens expire on 31 December 2026 (the Ministry proposed keeping them, but no regulation exists yet). Below is every date in a single table, plus what each one means for your business — and a checklist so nothing slips through.

KSeF Tokens and 2027: Why We Built Biurko on Certificates From Day One
KSeF & e-invoices
179

KSeF Tokens and 2027: Why We Built Biurko on Certificates From Day One

Under the rules currently in force, December 31, 2026 is the last day KSeF tokens work, and from January 1, 2027 certificates take over authentication with Poland's mandatory national e-invoicing system. At consultations on June 9, 2026 the Ministry of Finance proposed keeping tokens, with a validity of 1 to 365 days — a proposal, not yet a regulation, so moving to a KSeF certificate is the safer choice. Either way one thing holds: the second QR code (KOD II) in offline modes requires a certificate, which is why Biurko has run on Authentication- and Offline-type certificates since its first integration release (it does not support tokens).

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