KSeF deadlines 2026-2027 and what they mean for a JDG

KSeF, the Polish National e-Invoicing System, started in stages. If you run a JDG (a sole proprietorship), several dates are important. This guide puts the dates in order. It explains what each date means in practice.

This is general information, not tax advice. Ask your accountant which rule applies to you. Also read the official pages at ksef.podatki.gov.pl and podatki.gov.pl, because the rules and wording can change.

The short version

• From 1 February 2026, all taxpayers can receive invoices through KSeF, and must be able to do so.
• From 1 February 2026, issuing through KSeF is mandatory for firms whose 2024 sales were more than 200 million PLN.
• From 1 April 2026, issuing through KSeF is mandatory for all other taxpayers.
• Until 31 December 2026, taxpayers whose invoices total no more than 10,000 PLN gross per month can issue outside KSeF.
• From 1 January 2027, penalties for breaking the KSeF rules apply.

Today is the start of November 2026. The key question for most JDG owners is: what must I prepare before 1 January 2027?

1 February 2026: receiving

From this date, KSeF delivers invoices issued through KSeF to the buyer. Receiving works for all taxpayers, of any size.

This is what it means for you. If a supplier issues an invoice to you through KSeF, the legal invoice is the invoice in KSeF. An email attachment is only a courtesy copy. Check KSeF regularly, or use software that pulls in purchase invoices for you. Your accountant also needs access to these invoices.

1 February 2026: the largest firms

The first group to issue through KSeF was companies with sales above 200 million PLN in 2024. A JDG is very unlikely to be in this group. The date is still important, because many of your clients can be in this group. They send you invoices through KSeF from that date.

1 April 2026: everyone else

From 1 April 2026, issuing invoices through KSeF became mandatory for all other taxpayers. This includes nearly every JDG that issues invoices to other businesses.

On this date, the system moves from large companies to small companies. If you invoice a Polish company, that company expects to receive the invoice in KSeF.

The 10,000 PLN monthly transition

Smaller operators got extra time. A taxpayer whose invoices total no more than 10,000 PLN gross in a month can issue outside KSeF until 31 December 2026.

Note these points:

• The limit is for the total value of the invoices that you issue in a month. The value is gross (it includes VAT).
• It is a transition, not a permanent exemption. It ends on 31 December 2026.
• The official rules explain how to count the total. They also explain what happens in the month when you go over the limit. Read the official page or ask your accountant. Do not guess.
• If you are far below the limit, you can be tempted to wait. Consider if waiting is a good decision. You must set up access in the end. It is easier to do this in a quiet month than in a hurry.

1 January 2027: penalties

Penalties for breaking the KSeF rules start on 1 January 2027. Until then, the system is in a softer period. After this date, you can receive financial penalties. This applies if you issue invoices incorrectly, or outside KSeF when you must use it.

The law has the exact penalty rules and amounts. What applies to you depends on your situation. Ask your accountant. In practice, your process must work by 2027.

Offline modes

KSeF has offline modes. Use them when you cannot reach the system, or when the system is not available. In an offline mode, you prepare the invoice. You give your client a version with a code, so that the client can check it. After that, you send the invoice to KSeF.

These modes are a safety net. They are not a normal way of working. The official documentation has the rules for each mode, including how quickly you must upload. Fiskora does not currently list offline issuing among its features. Check our help pages before you rely on it.

What this means for a JDG, month by month

Now to December 2026. If you are below the 10,000 PLN monthly limit, you can still issue outside KSeF. If you are above it, you must already issue through KSeF. In both cases, use this time to prepare:

1. Create the KSeF certificate (see our guide on the KSeF certificate).
2. Connect your invoicing software.
3. Test with the KSeF test environment first.
4. Agree with your accountant how they see your invoices.

1 January 2027. Penalties apply. By then, your process must be routine: issue the invoice, send it to KSeF, store the UPO, and email the PDF.

Foreign clients and the deadlines

Many foreign clients are not in KSeF. They cannot receive invoices there. The deadlines above are for the Polish rules for Polish invoicing. The handling of a specific invoice to a foreign client depends on the case. Ask your accountant. See our guide on invoicing foreign clients.

Things people often get wrong

• They think that a PDF by email is enough. When you must use KSeF, the invoice in KSeF is the real invoice.
• They forget purchase invoices. Receiving through KSeF applies to all taxpayers since 1 February 2026.
• They think that the 10,000 PLN rule lasts forever. It ends on 31 December 2026.
• They leave the certificate setup to the last week. Logging in, generating the certificate and testing all take time. This is more true if you must first arrange an electronic login.

A sensible plan

If you have not started, work backwards from 1 January 2027. Set up your KSeF certificate in November. Test in December. Begin to issue real invoices when you are comfortable. The first real invoice in Fiskora is free. You can try the whole process before you pay anything.

If you are not sure, send your accountant the question and the date. Your accountant knows which rule applies to your case.