KSeF & e-invoices

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

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

18136

Jun 19, 2026

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 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. 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

19621

Jun 18, 2026

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

From 1 February 2026, Poland's largest taxpayers — and from 1 April 2026, almost everyone else — 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

19967

Jun 17, 2026

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its rollout pushed back so many times that most business owners are still working from a version that's two amendments out of date.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. That means we're now inside the so-called protection year — the rules are live, but administrative penalties aren't being applied yet. That window closes on 31 December 2026. From 1 January 2027, full penalties kick in, authentication tokens disappear, and the smallest companies join the system. 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

156

Jun 7, 2026

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. On June 9, 2026 the Ministry of Finance proposed keeping tokens permanently, with a validity of 1 to 365 days — a proposal, not yet a regulation. Either way one thing holds: offline modes require a certificate, which is why Biurko has run on type 1 and type 2 certificates since its first integration release.