EU E-invoicing overview
KSeF mandatory from Feb 2026

Poland KSeF Guide

Poland's national e-invoicing system (KSeF) became mandatory for large businesses in February 2026 and for all businesses from April 2026. KSeF is fundamentally different from Peppol: it is a government-hosted clearing system where every invoice passes through the Ministry of Finance.

System

KSeF (Ministry of Finance)

Format

FA(2) XML

Large taxpayers

1 Feb 2026

All others

1 Apr 2026 / 1 Oct 2026

How KSeF works

KSeF is a clearance model. Unlike Peppol (where invoices are routed peer-to-peer), every KSeF invoice passes through a central government system before it is legally considered issued.

1

Generate FA(2) XML

Your accounting system generates an invoice in the FA(2) XML schema defined by the Polish Ministry of Finance.

2

Submit to KSeF

The XML is submitted to the KSeF API. The Ministry validates the structure and, if valid, returns a unique KSeF number (Numer KSeF) and a timestamp.

3

Invoice is issued

The invoice is legally issued at the moment KSeF assigns the number. The buyer can retrieve the invoice directly from KSeF or receive it from the seller.

The Numer KSeF is a 36-character alphanumeric identifier that serves as proof the invoice was legally issued. It must be included on any printed or PDF version of the invoice sent to the buyer.

Mandate timeline

Live

1 Jan 2022

KSeF voluntary launch

Polish Ministry of Finance launched KSeF as an opt-in pilot. Businesses could start issuing and receiving FA(2) invoices voluntarily.

Live

1 Feb 2026

Mandatory: large taxpayers

Businesses with annual turnover above PLN 200 million (approx. EUR 45m) must issue all domestic B2B invoices via KSeF.

Live

1 Apr 2026

Mandatory: all other taxpayers

All remaining Polish VAT-registered businesses (except micro below PLN 200k) must use KSeF for domestic B2B invoices.

Upcoming

1 Oct 2026

Mandatory: micro taxpayers

Businesses with turnover below PLN 200,000 and businesses exempt from VAT must comply with KSeF requirements.

Cross-border sellers: what you need to know

You are selling TO a Polish buyer

If you are a non-Polish business issuing invoices to a Polish company, KSeF does not apply to you. Cross-border invoices are exempt from mandatory KSeF submission.

Your Polish buyer will receive the invoice as usual (PDF, email, or Peppol). They do not need to register your invoice in KSeF.

However: if your Polish buyer asks you to deliver invoices in FA(2) format via KSeF, you can do so voluntarily (requires a Polish KSeF API token granted by the buyer).

You are a Polish company selling abroad

Export invoices and intra-EU B2B invoices to non-Polish buyers are exempt from mandatory KSeF submission.

You still need to issue these invoices under Polish VAT rules, but you do not need to submit them to the KSeF API. You can still do so voluntarily.

For cross-border invoices you want to archive with tamper-evidence and RFC 3161 timestamps, SealDoc handles this independently of KSeF.

KSeF vs Peppol: key differences

KSeF (Poland) Peppol (EU)
Model Clearance: invoice passes through government Decentralised: peer-to-peer routing via Access Points
Format FA(2) XML (Polish-specific) UBL 2.1, CII, Factur-X (EN 16931)
Scope Domestic B2B and B2G (Poland only) Cross-border EU B2B and B2G
Legal timestamp KSeF assigns timestamp at submission RFC 3161 timestamp via TSA (optional but recommended)
Archival KSeF stores invoices for 10 years on government servers Buyer/seller responsible for own archival
Cross-border Exempt for non-domestic transactions Designed for cross-border EU invoicing

Frequently asked questions

When did KSeF become mandatory in Poland?
KSeF became mandatory for large taxpayers (annual turnover above PLN 200 million) on 1 February 2026. All other VAT-registered businesses must comply from 1 April 2026. Micro-taxpayers (turnover below PLN 200,000) and VAT-exempt businesses have until 1 October 2026.
Does KSeF apply to cross-border invoices?
No. Cross-border invoices (B2B transactions where the buyer is not a Polish taxpayer) are exempt from mandatory KSeF submission. This includes intra-EU sales and exports. Polish sellers may use KSeF voluntarily for such transactions.
What format does KSeF use?
KSeF uses the FA(2) XML schema (previously FA_VAT). This is a Polish-specific format defined by the Ministry of Finance. It is not based on EN 16931 and is not compatible with Factur-X or XRechnung.
Does KSeF replace the need for invoice archival?
KSeF stores submitted invoices on government servers for 10 years. However, businesses should still maintain their own archive. The KSeF-assigned timestamp and Numer KSeF serve as proof of legal issuance, but businesses are responsible for the full audit trail including payment confirmation and related documents.
My Polish customer is asking for a KSeF invoice. What should I do as a foreign seller?
As a non-Polish seller, you are not required to use KSeF. Explain to your Polish customer that cross-border invoices are exempt from KSeF. You can send a structured invoice (Factur-X or UBL) or a regular PDF. Both are accepted for non-domestic transactions. If they insist on a KSeF-formatted invoice, they would need to grant you API access, which is unusual for regular suppliers.

Check if your Polish partners are on Peppol

Peppol lookup is free. For cross-border invoices to Polish buyers, Factur-X or UBL is the most interoperable option.

Peppol Check Validate Factur-X