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

Every KSeF deadline in one table

1 February 2026 — large companies start, everyone must receive

The first hard date covers two different groups.

Large taxpayers — companies whose 2024 sales including tax exceeded PLN 200 million — must issue invoices through KSeF from this date (source: Biznes.gov.pl).

But there's a second part that's easy to miss: receiving invoices via KSeF became mandatory for all taxpayers on 1 February 2026, regardless of when they themselves start issuing (source: Biznes.gov.pl). If a large supplier sits anywhere in your supply chain, their invoice lands in KSeF from February — and you have to be able to retrieve it there, even as a JDG (sole proprietorship).

This date also brings two operational tools into production: the KSeF certificate and offline24 mode, which lets you issue an invoice outside the system and send it in by the next business day at the latest (Article 106nda of the VAT Act). We cover certificates in more detail in our offline24 guide.

1 April 2026 — mandatory for (almost) everyone

The second wave covers essentially the entire B2B market: small businesses, sole proprietors, companies, and both VAT-registered and VAT-exempt taxpayers. From this date, issuing invoices in KSeF is mandatory for them (source: Biznes.gov.pl).

One exception: the smallest taxpayers. Until 31 December 2026 those whose monthly gross value of B2B invoices subject to the KSeF obligation does not exceed PLN 10,000 may issue 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 — those are separate exceptions, not a condition of the cap. Exceeding the cap is irreversible: from the invoice that crossed it, you issue in KSeF.

Until 31 December 2026 — no administrative fines yet, and deferrals

This is where we are right now. Until 31 December 2026, the administrative fines under Article 106ni of the VAT Act do not apply — time to adapt processes and systems (source: ksef.podatki.gov.pl).

Watch out for one trap: the absence of fines covers only KSeF-specific administrative penalties. Fiscal-criminal liability (under the Fiscal Penal Code) for unreliable invoicing or refusing to issue an invoice applies normally throughout 2026.

Two things also end during this period under the current rules:

• the deferral for the smallest taxpayers (PLN 10,000/month cap) — December 2026 is the last month without the obligation,

• tokens as an authentication method — usable only through 31 December 2026 (at consultations on 9 June 2026 the Ministry proposed keeping them, but no regulation exists yet).

1 January 2027 — the grace period ends

Three things converge at the turn of 2026 and 2027:

1. The smallest taxpayers (the PLN 10,000 monthly cap ends) come under the obligation to issue through KSeF.

2. Administrative penalties under Article 106ni of the VAT Act take effect under the current act. On 16 September 2026 the Ministry announced it will move them to 1 January 2028; that is a bill not yet passed, and it moves only the penalties. The maximum is up to 100% of the VAT shown on an invoice issued outside KSeF, or up to 18.7% of the total amount due for invoices without VAT.

3. Tokens. Under the current rules they expire on 31 December 2026. The Ministry proposed keeping them, but no regulation exists yet, so moving to a KSeF certificate is the safer choice (a qualified signature / seal also works for authentication).

The legal basis for the whole timeline is the Act of 5 August 2025 (Journal of Laws 2025, item 1203), amending the VAT Act.

Technical dates that are easy to forget

• 1 November 2025 — applications opened for the KSeF certificate (in the KSeF 2.0 Taxpayer Application / certificate module) and the KSeF 2.0 DEMO environment went live. The certificate is free and valid for about two years.

• 1 January 2026 — anyone wanting to issue invoices with attachments in the FA(3) structure must first file a notification with the Ministry of Finance (approval can take up to 30 days).

• Consumer invoices (B2C) do not have to go through KSeF — invoices to private individuals not running a business can be issued the usual way (paper/PDF), or the sale recorded on a cash register. You may also issue one in KSeF voluntarily.

Checklist — what to do and when

• [ ] Today: confirm your company is already issuing in KSeF (mandatory for most since 1 April 2026).

• [ ] Today: make sure you're retrieving purchase invoices from KSeF — mandatory for everyone since 1 February 2026.

• [ ] Before the end of 2026: get a KSeF certificate if you're still on a token (a token cannot issue one — the first login requires a qualified signature, seal or Profil Zaufany).

• [ ] Before 1 January 2027: move from the token to a certificate. Under the current rules the token stops working on 31 December 2026 (the Ministry proposed keeping tokens, but no regulation exists yet).

• [ ] If you're within the PLN 10,000/month B2B cap: plan your KSeF entry for 1 January 2027 at the latest.

• [ ] All of 2026: treat the absence of administrative fines as time to prepare, not as a pass on accurate invoicing (fiscal-criminal rules still apply). To practise without legal effect, use the Biurko demo (demo.biurko.io, 7-day access, the KSeF demo environment). An account on app.biurko.io sends invoices to production KSeF, so every invoice you send there is real.

Summary

The whole calendar boils down to three points: most companies have been issuing in KSeF since April 2026, administrative fines do not apply yet (under the current act they start on 1 January 2027; a move to 2028 is announced but not yet law), and at the turn of 2026 and 2027 the grace period ends, the smallest-firm deferral closes and, under the current rules, tokens expire. The rest is detail that a good system handles for you. Biurko tracks certificate expiry, resubmits offline24 invoices automatically and shows submission statuses, and the obligations calendar lists the deadlines. Set up your company in Biurko — 14 days of the TEAM plan without a card, then the free FREE plan.

FAQ

When does KSeF become mandatory? Issuing invoices in KSeF is mandatory from 1 February 2026 for large companies (2024 sales > PLN 200M) and from 1 April 2026 for everyone else. The smallest taxpayers join on 1 January 2027; until then they may issue outside KSeF if the monthly gross value of their B2B invoices subject to the obligation does not exceed PLN 10,000. Receiving invoices has been mandatory for all taxpayers since 1 February 2026.

Do small businesses and sole proprietors have to use KSeF? Yes. As a rule the obligation covers all VAT taxpayers (active and exempt), including sole proprietorships (JDG). The exception is the smallest taxpayers with a monthly gross value of B2B invoices subject to the obligation up to PLN 10,000 — they have a deferral until 1 January 2027, but must still receive invoices from February 2026.

When do KSeF penalties start? 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. There are no such penalties in 2026. The maximum fine is up to 100% of the VAT on an invoice issued outside KSeF (or up to 18.7% of the total amount due for an invoice without VAT).

How long can I keep using KSeF tokens? Under the current rules KSeF tokens 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. Tokens don't support offline modes anyway, so it's worth setting up a certificate early.

Do invoices to private individuals (consumers) go to KSeF? They don't have to. Invoices to private individuals not running a business are not covered by the KSeF obligation, but you may issue them there voluntarily. You can also issue them the usual way — on paper or as a PDF — or record the sale on a cash register.