5 KSeF Myths Businesses Still Believe in 2026

Myth 1: "KSeF will be postponed again — it isn't live yet"

The obligation itself won't be postponed. The schedule is written into the amended VAT Act and rolls out in stages (the announced postponement concerns only the penalties — see myth 5):

The full timeline and legal basis are published on ksef.podatki.gov.pl.

If you run an ordinary VAT-registered business and aren't a billion-zloty corporation, your deadline was 1 April 2026 — for most readers, that's already in the past, not the future. The smallest taxpayers join on 1 January 2027.

Myth 2: "KSeF only affects large companies, not my small business"

This is a half-truth that bites. The obligation to issue invoices arrived in stages, but the obligation to receive invoices through KSeF applied to every business from 1 February 2026, regardless of size. Your supplier can issue you an invoice in KSeF and will not email it. If you never open the system, you simply won't see it.

The second point is the famous PLN 10,000 threshold. It is not a "small-business exemption." Until 31 December 2026 taxpayers whose monthly gross value of B2B invoices subject to the KSeF obligation does not exceed PLN 10,000 may issue them outside KSeF. The cap does not count invoices to consumers, receipts with a NIP, simplified invoices up to PLN 450, or sales from a cash register. Exceeding the cap is irreversible: from the invoice that crossed it, you issue in KSeF, with no grace period. And the threshold only lasts until the end of 2026 — from 1 January 2027 everyone is in.

The scope of the obligation is set out on the official MF page.

Note on terms: JDG (jednoosobowa działalność gospodarcza) is a Polish sole proprietorship; NIP is the Polish tax ID; MF is the Ministry of Finance.

Myth 3: "I have to issue consumer (B2C) invoices in KSeF too"

You don't. Invoices to private individuals who are not running a business may be issued in KSeF voluntarily — the choice rests with you as the seller (source: MF).

In practice this means a consumer invoice follows a different path than a B2B invoice. Good software should tell them apart automatically and mark the document as issued outside KSeF, so you don't accidentally push data into the system that never needed to be there.

Watch for one trap: if a private individual asks for an invoice and provides a NIP, what matters is whether they are buying as a business. Then it is a B2B sale covered by the obligation, not plain B2C.

Myth 4: "If KSeF goes down or I lose internet, I can't issue an invoice"

You can. The legislator anticipated outages and defined what to do. In short:

• Offline24 mode — you can choose it at any time, even when KSeF is working; you issue the invoice outside KSeF and send it to the system by the next business day at the latest.

• Unavailability announced by MF (Art. 106nh) — you send the invoice on the next business day after it ends.

• Outage declared by MF in the official bulletin (BIP) (emergency mode, Art. 106nf) — you have 7 business days to submit the invoices after it ends.

• Total outage (Art. 106ne(3), Art. 106ng) — you do not send the invoices afterwards, and there are no QR codes.

In every case sales continuity is preserved — you issue the invoice "for now," and it reaches KSeF (except after a total outage) with the right flag (in the JPK file, the OFF marker). You can monitor the current system status via MF announcements.

The practical takeaway: offline mode isn't a rare exception to ignore — it's a standard part of the process. Your invoicing tool must support it, not block a document "because there's no connection."

Myth 5: "I'll be fined for every KSeF mistake straight away"

Not in 2026. The whole of 2026 is a transition period: the administrative penalties under Article 106ni of the VAT Act do not apply yet, so tax authorities do not impose them for technical slips, submission delays, or errors caused by rolling out the system.

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. The penalties are steep:

• up to 100% of the VAT shown on the invoice (when a document was issued outside the system despite the obligation),

• up to 18.7% of the total amount due for invoices with no VAT shown (e.g. VAT-exempt taxpayers).

A concrete figure: an invoice of PLN 100,000 net (VAT PLN 23,000) issued outside KSeF while the penalties apply carries a penalty of up to PLN 23,000 — for a single document. The penalty is calculated on each invoice separately.

Just don't confuse "no penalties" with "anything goes." Already today, a paper invoice from an entity that is subject to the obligation is not a valid invoice under the Act — your counterparty cannot deduct VAT from it. Fiscal-penal liability also applies. The absence of administrative penalties in 2026 is time to get your processes right, not to postpone them.

Checklist: act before the myths catch up with you

1. Check your deadline — if you're under PLN 200 million, your issuing obligation started on 1 April 2026.

2. Turn on KSeF invoice receiving now — mandatory for everyone since 1 February 2026.

3. Separate your B2B and B2C flows — don't push consumer invoices into KSeF unless you want to.

4. Test offline24 mode before you actually need it — confirm your system can issue an invoice with no connection.

5. Generate KSeF 2.0 authentication (a KSeF certificate or a qualified signature/seal) — don't leave it to the last minute.

6. Use 2026 as a buffer — fix your processes while mistakes don't end in fines.

7. Verify changes at the source — KSeF rules are still being refined; rely on MF announcements, not hearsay.

Conclusion

The costliest KSeF myth is the belief that "it isn't here yet." It is, it's mandatory, and 2026 is the time to prepare before the penalties start to apply. The rest — about large companies, B2C, outages and sanctions — collapses the moment you check it against the Act.

Biurko walks you through KSeF so you don't have to memorize every exception: it lets you issue an invoice in offline24 mode, sends it to KSeF automatically, and the obligations calendar shows the deadlines. Set up your company in Biurko at biurko.io — 14 days of the TEAM plan without a card, then the free FREE plan — and stop guessing what applies to you.

FAQ

Is KSeF already mandatory in 2026? Yes. From 1 February 2026 for companies with sales above PLN 200 million, and from 1 April 2026 for all other VAT taxpayers. The smallest taxpayers join on 1 January 2027; until then those whose monthly gross value of B2B invoices subject to the obligation does not exceed PLN 10,000 may issue outside KSeF. Receiving invoices through KSeF has applied to everyone since 1 February 2026.

Do small businesses and sole proprietors have to use KSeF? Yes, in stages. Receiving invoices applies to everyone from 1 February 2026. Issuing starts on 1 April 2026, while the smallest sellers (until 31 December 2026 outside KSeF, with monthly gross B2B invoices up to PLN 10,000) have until 1 January 2027. That threshold is a transitional cap, not a permanent exemption.

Do I have to issue consumer invoices in KSeF? No. Invoices to private individuals not running a business (B2C) can be issued in KSeF voluntarily — it's the seller's choice. However, if the buyer is buying as a business (provides a company NIP, the Polish tax ID), it is a B2B sale covered by the obligation.

What do I do when KSeF is unavailable? You can issue the invoice in offline24 mode (always available) and send it to KSeF by the next business day at the latest; after an unavailability announced by MF, on the next business day after it ends. If an outage is announced in the BIP bulletin, you have 7 business days after it ends; after a total outage you do not send the invoices. Sales can continue without interruption.

When do penalties for not using KSeF start? Under the current act, penalties under Article 106ni (up to 100% of the VAT on the invoice) apply from 1 January 2027; the Ministry of Finance announced on 16 September 2026 that it will move them to 1 January 2028 — a bill not yet passed. 2026 is a period with no administrative penalties for errors. Fiscal-penal liability still applies, and a paper invoice from an obligated entity does not grant the right to deduct VAT.