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e-Invoicing PolandMandatory, phasedLast reviewed October 2026e-Invoicing in Poland: KSeF explained
Poland requires domestic invoices between businesses to be issued as structured XML in KSeF, the central system run by the Ministry of Finance. The obligation started on 1 Feb 2026 for the largest taxpayers and on 1 Apr 2026 for all other businesses. Only the smallest firms still have a transition, which ends on 31 Dec 2026, and no penalties apply for KSeF errors until at least the end of 2026.
General information only, not tax advice. Rules change, so check the official sources at the bottom of this page before you act.
The mandate
Krajowy System e-Faktur (KSeF) - Polish National e-Invoicing System
Who must issue
All taxpayers established in Poland that issue domestic invoices to other businesses, whether they are active VAT payers or VAT-exempt. Invoices to consumers (B2C), transport tickets that serve as invoices and OSS/IOSS invoices are outside the obligation. Very small businesses with invoiced sales up to PLN 10,000 gross per month can stay outside KSeF until the end of 2026.
How it works
ERP or the free Ministry application creates the invoice as FA(3) XML → sent to KSeF through the API → KSeF validates it and assigns a KSeF number → invoice is available to the buyer in KSeF → buyer retrieves it and books it
System type
Clearance
The tax authority checks and approves each invoice before it counts as valid.
Public sector (B2G)
Mandatory via KSeF from 1 Feb / 1 Apr 2026
Business to business (B2B)
Mandatory 1 Feb 2026 (large), 1 Apr 2026 (others)
Consumers (B2C)
Not required (voluntary in KSeF)
Key dates for Poland
- 1 Jan 2022KSeF opens for voluntary use
- 1 Feb 2026Mandatory issuing for taxpayers with 2024 sales above PLN 200 million (incl. VAT); all businesses must be able to receive invoices in KSeF
- 1 Apr 2026Mandatory issuing for all other taxpayers, including VAT-exempt ones
- Sep 2026Ministry of Finance publishes a draft law to move the start of KSeF penalties to 1 Jan 2028 (draft, not yet law)
- 31 Dec 2026Transition ends for very small businesses (sales up to PLN 10,000 gross per month) and for invoices issued from cash registers; current law starts KSeF penalties on 1 Jan 2027
What the invoice contains
A structured invoice exists legally once it is sent to KSeF, passes validation and receives a KSeF number. The required format is the FA(3) XML schema published by the Ministry of Finance, and invoices are sent through the KSeF API or the free taxpayer application. A PDF or paper copy is only a visual copy, not the invoice. KSeF stores invoices for 10 years, and the buyer is identified by the Polish tax number (NIP).
What your ERP has to deliver
The ERP must produce FA(3) XML, authenticate to the KSeF API with a token or certificate, and store the KSeF number against each invoice. It must handle incoming invoices pulled from KSeF, corrections issued as structured corrective invoices (the old correction note no longer exists), and the offline modes. Offline24 mode lets a business issue the invoice and send it to KSeF by the next working day, and a separate failure mode applies when KSeF is unavailable. Invoice archiving and the KSeF number in payment references need to be planned.
The data flow, step by step
Practical insights
- Receiving is mandatory for everyone from 1 Feb 2026, even for businesses whose own issuing started later. A company cannot refuse a KSeF invoice, and the invoice is treated as delivered when it is available in KSeF.
- The 2026 grace period applies to penalties, not to the obligation. An invoice sent outside KSeF in 2026 may not be fined, but it is not a valid structured invoice for the buyer, and the VAT treatment can still be challenged.
- From 1 Jan 2027, the current rules require the payer to put the KSeF number in the payment reference for transfers between VAT payers. Finance teams should plan how payment runs will pick up that number.
- Offline24 has no end date, so it is a normal fallback and not only an emergency tool. Issuer certificates are needed for offline use and must be obtained in advance.
Common pitfalls
- Treating a PDF sent by email as the invoice. The legal invoice is the XML in KSeF, and the buyer may not have it if it was never sent.
- Waiting for the penalty start date. Penalty dates may move, but the obligation and the VAT consequences of a missing invoice do not.
- Forgetting receiving. Accounts payable has to read invoices from KSeF, not from email, from 1 Feb 2026.
- Using the old correction note for errors. Corrections now have to be made with a corrective invoice.
Linked obligations in Poland
e-Invoicing Poland: questions, answered
Official sources
Keep this guide
Download the Poland e-Invoicing guide as a PDF. It has the same content as this page.