Quick answer
Since 1 February 2026, taxpayers with 2024 sales above PLN 200 million must issue invoices in KSeF, and every business receives invoices through it. Since 1 April 2026 the duty covers other taxpayers, including VAT-exempt ones. Businesses invoicing up to PLN 10,000 a month may stay outside KSeF until 31 December 2026. Penalties apply from 1 January 2027.
Key dates
| When | What changes |
|---|---|
| 1 February 2026 | Mandatory issuing for taxpayers with 2024 sales over PLN 200 million; all businesses receive via KSeF. |
| 1 April 2026 | Mandatory issuing for all other taxpayers, including VAT-exempt businesses. |
| Until 31 December 2026 | Transition: offline24 mode for everyone, cash-register invoices and small sellers (up to PLN 10,000 a month) outside KSeF, no penalties. |
| 1 January 2027 | KSeF mandatory for the smallest taxpayers too; penalties start. |
How KSeF works
An invoice is created as an XML file in the FA(3) structure and sent to KSeF, which gives it a KSeF number. Only then is it legally issued. Polish business buyers download it from KSeF. A PDF is not a structured invoice, but a visualisation with a QR code can be shared.
The Ministry of Finance offers free tools: the Aplikacja Podatnika KSeF web app, e-mikrofirma in e-Urząd Skarbowy and a mobile app. Accounting software can connect through the KSeF API.
Offline modes
- Offline24: issue outside the system with QR codes and send to KSeF by the next business day. Available to everyone without a reason until the end of 2026.
- KSeF unavailability: after an announced outage, send by the next business day after it ends.
- Failure mode: after an announced failure, send within 7 business days.
Foreign businesses and what is outside KSeF
KSeF applies to taxpayers established in Poland (and fixed establishments involved in the sale). Invoices to consumers, proformas, quotes and the simple rachunek issued by VAT-exempt sellers are outside KSeF. Invoices from a Polish business to a foreign client are still issued in KSeF and then sent to the client in an agreed way.
Where Invoiceferry fits
Invoiceferry does not send invoices to KSeF or create FA(3) files. If KSeF applies to you, issue the invoice in the free Aplikacja Podatnika KSeF or your accounting software. Use Invoiceferry for proforma invoices, quotes, consumer invoices and receipts, and a clear PDF for foreign clients alongside the KSeF invoice. See our Poland invoice template.
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Open the free invoice makerFrequently asked questions
Is a PDF invoice valid in Poland?
For domestic B2B sales by a business that KSeF applies to, no: the invoice must be issued in KSeF. PDFs remain fine for consumers, proformas and quotes.
Do foreign companies have to use KSeF?
Generally only if they have a fixed establishment in Poland involved in the sale. A foreign seller registered for Polish VAT without one may use KSeF voluntarily. Check with a Polish adviser.
What format does KSeF use?
The FA(3) logical structure, an XML schema published by the Polish Ministry of Finance. It is not Peppol or EN 16931 UBL.
When do KSeF penalties start?
From 1 January 2027. Breaches in 2026 are not penalised under the special KSeF penalty rules.
Can Invoiceferry issue KSeF invoices?
No. It makes PDFs and some EU e-invoice formats, but not FA(3), and it does not connect to KSeF.
Related guides
This guide is a summary, not legal or tax advice. Rules and dates change, so check with the tax authority or your adviser. Updated: 2026-11-06.