The short answer: the big deadlines are behind us
The schedule is no longer a draft or a vague intention. It's written into the Act of 5 August 2025 (Journal of Laws 2025, item 1203), and the market already operates by it:
1 February 2026 — mandatory KSeF invoicing for taxpayers whose VAT-inclusive sales exceeded PLN 200 million. The same day, mandatory receipt of invoices through KSeF began — for everyone, regardless of company size.
1 April 2026 — mandatory KSeF invoicing for all remaining businesses, including micro-firms and JDG (Poland's sole proprietorship).
These dates are closed. There is no bill in the legislative pipeline that would reverse them. So the question "will they postpone it again?" — asked about the start of the obligation — is already moot. The start happened.
Why everyone expected another slip
It's worth understanding where that instinct comes from, because it's exactly what keeps people waiting.
KSeF was originally meant to be mandatory from 1 July 2024. In January 2024, the Ministry of Finance announced a postponement and a system audit — it had found defects too serious to ignore. KSeF 2.0 was built, with a new FA(3) invoice schema. The date moved to February 2026 (large firms), then April 2026 (everyone else) and January 2027 (the smallest) were added.
Every postponement reinforced the belief that "they'll just push it again." But the difference between 2024 and 2026 is fundamental. In 2024, the government was delaying a system that didn't work. In 2026, the system works, it's been tested, and it's broadly deployed. There's nothing left to fix with an audit — there's something to enforce.
What is genuinely still in play
Uncertainty hasn't vanished; it has moved to smaller, technical pieces. These are the ones worth tracking.
A transition window for the smallest firms (until 31 December 2026). Micro-businesses whose invoices in a given month document sales of up to PLN 10,000 gross may, until the end of 2026, issue paper or electronic invoices outside KSeF. Once that monthly limit is exceeded, KSeF becomes mandatory. It's a temporary relief, not an exemption.
Penalties from 1 January 2027. From that date the KSeF obligation covers everyone, including the smallest. That's also when administrative fines begin — up to 100% of the VAT amount on an invoice issued outside KSeF (or up to 18.7% of the gross value where the invoice carries no VAT). From 1 January 2027 there's also a duty to quote the KSeF number in payments between taxpayers, including the split-payment mechanism (MPP).
Tokens — and this is fresh. Until recently the schedule was clear: authorization tokens valid until 31 December 2026, then certificates only from 2027. But at consultations on 9 June 2026, the Ministry of Finance presented a package of seven changes that extends token validity — they are now set to remain active at least into 2027 (KSeF consultations).
Notice the direction of these changes: the Ministry is softening rules and extending transitional relief, but it is not rolling back the core obligation. That matters, because many people are waiting for a "postponement" and instead getting something different — minor conveniences for those who are already inside the system.
The "no penalties in 2026" trap
The most common misreading is: "there are no fines until the end of 2026, so I have time." That's a trap.
First, the reprieve concerns administrative monetary penalties. The provisions of the Fiscal Penal Code apply from the moment the obligation takes effect — for instance, for fraudulent invoices documenting events that never happened. There is no grace period there.
Second, the duty to receive invoices through KSeF applies to everyone from 1 February 2026. If your counterparty issues an invoice in KSeF and you can't retrieve it, the problem is yours — penalties aside.
Third, 1 January 2027 is not a distant abstraction. It's a matter of months. Companies that "wait for the penalties" will start implementing exactly when the buffer is gone — with no margin for integration issues, permissions, or testing.
How to prepare so no date surprises you
The trick isn't predicting when the Ministry will change something. It's separating the hard dates (already in force, won't move) from the soft ones (penalties, reliefs, technical detail — which can shift, usually toward leniency), then building foundations that survive either outcome.
Sort out authentication for the long run, not for now. Apply for a KSeF certificate. Tokens were extended, but the direction is clear — the certificate is the destination, and it's also a precondition for issuing invoices in offline24 mode when the system is unavailable.
Make sure you can receive FA(3) invoices. This is mandatory for everyone from 1 February 2026 — and the most commonly overlooked, because "I mostly issue invoices."
Have an outage procedure. Offline24 mode, codes, resubmission deadlines — not a curiosity, but a real scenario when KSeF is briefly unavailable.
Follow the source, not rumors. The schedule and announcements live at ksef.podatki.gov.pl. Base decisions on them, not on "I heard they're pushing it again."
Don't plan your rollout around a hoped-for delay. Treat any softening as a bonus, not as the basis of your plan.
Bottom line
KSeF's two most important dates — 1 February and 1 April 2026 — are behind us. What's left is a transition window through the end of 2026, penalties from 1 January 2027, and minor technical adjustments that lean toward leniency rather than reversal. The cheapest strategy is to be ready for the hard dates and treat reliefs as a bonus.
At Biurko we track the Ministry's changes for you — from the FA(3) schema to certificates and offline24 mode — so the next amendment is our problem, not yours. Create an account and try Biurko free for 14 days at biurko.io.
FAQ
Will KSeF deadlines be postponed again? The main start dates — 1 February and 1 April 2026 — have already passed and won't be reversed. No bill in the pipeline would defer them. The 2026 changes concern technical detail and transitional relief, not a rollback of the obligation itself.
Are there penalties for KSeF in 2026? Administrative fines only begin on 1 January 2027. But Fiscal Penal Code provisions — for example, for fraudulent invoices — already apply, with no grace period. The absence of administrative penalties does not mean the absence of an obligation.
Will KSeF tokens disappear at the end of 2026? Tokens were originally set to expire on 31 December 2026. At consultations on 9 June 2026, the Ministry of Finance announced an extension of their validity at least into 2027. KSeF certificates remain the long-term solution, so it's worth applying for one now.
When is KSeF mandatory for a sole proprietorship (JDG)? For sole proprietorships, mandatory KSeF invoicing applies from 1 April 2026. The smallest firms (monthly sales up to PLN 10,000 gross) may use the transition window until 31 December 2026, and from 1 January 2027 the obligation covers everyone.
What do I do if KSeF is unavailable? You can use offline24 mode and issue an invoice outside the system, provided you hold an invoice-issuer certificate. The document must then be sent to KSeF without undue delay — as a rule, by the next business day. If the Ministry officially declares an outage, longer resubmission deadlines apply.