How to Open and Read a KSeF XML Invoice (FA(3) Fields Explained)
What a KSeF e-invoice XML file is, how to open it without accounting software, and what fields like P_2, P_13_1, P_14_1 and P_15 mean in the FA(3) structure.
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The short answer
A KSeF invoice is an XML file in the FA(3) structure published by Poland's Ministry of Finance. Open it in the KSeF Taxpayer Application, in your accounting software, or in a browser-based KSeF invoice viewer that shows it as a normal invoice. A text editor also opens it, but you will see coded fields such as P_15 instead of labels.
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Why you are receiving XML invoices
Poland's National e-Invoice System (KSeF) became mandatory in stages: from 1 February 2026 for taxpayers whose 2024 sales exceeded PLN 200 million, and from 1 April 2026 for most other businesses. Taxpayers with monthly sales up to PLN 10,000 have a transition period until the end of 2026. Invoices issued in KSeF exist as structured XML, so suppliers, accountants and foreign partners increasingly send or receive the XML itself.
Check current rules and dates on the Ministry of Finance's KSeF site (ksef.podatki.gov.pl) before relying on them for compliance decisions.
Three ways to open the file
- KSeF Taxpayer Application (Aplikacja Podatnika KSeF): the free official web app. You log in to your company's KSeF account and can view and download invoices and their visualisations.
- Accounting or invoicing software: most Polish systems import FA(3) XML and show it as an invoice.
- Browser viewer without login: the ToolsWebPro KSeF viewer opens an XML file you already have, shows parties, lines, VAT and payment, and can print or save it as PDF. It does not connect to KSeF.
What the FA(3) fields mean
| Element | Meaning |
|---|---|
| Podmiot1 | Seller: NIP, name, address, contact details |
| Podmiot2 | Buyer: NIP, EU VAT number or other ID, name, address |
| P_1 / P_1M | Issue date / place of issue |
| P_2 | Invoice number |
| P_6 | Date of sale or service, if different from the issue date |
| KodWaluty | Currency code, such as PLN or EUR |
| P_13_1 / P_14_1 | Net amount / VAT at the basic rate (23% or 22%) |
| P_13_2 / P_14_2 | Net amount / VAT at the first reduced rate (8% or 7%) |
| P_13_3 / P_14_3 | Net amount / VAT at the second reduced rate (5%) |
| P_13_7 | Net amount of exempt supplies (zw) |
| P_15 | Total amount due |
| RodzajFaktury | Invoice type: VAT, KOR (corrective), ZAL (advance), ROZ (settlement), UPR (simplified) |
| FaWiersz | One invoice line: P_7 name, P_8A unit, P_8B quantity, P_9A unit net price, P_11 net value, P_12 VAT rate |
| Platnosc | Payment: due date (TerminPlatnosci), method (FormaPlatnosci), bank account (RachunekBankowy/NrRB) |
FormaPlatnosci uses codes: 1 cash, 2 card, 3 voucher, 4 cheque, 5 credit, 6 bank transfer, 7 mobile payment. Rates in P_12 can also be codes such as zw (exempt), oo (domestic reverse charge) or np (outside the scope of Polish VAT).
FA(3) or FA(2)?
Look at the xmlns attribute on the <Faktura> element. FA(3) files use http://crd.gov.pl/wzor/2025/06/25/13775/. Files with http://crd.gov.pl/wzor/2023/06/29/12648/ use the older FA(2) structure from the voluntary phase. The viewer shows which structure a file uses.
Limits of a readable copy
The XML in KSeF is the invoice. A printout or PDF made by a viewer is a convenience copy. Official visualisations for buyers outside KSeF, such as consumers and foreign customers, carry a QR code that leads to the invoice in KSeF; a browser viewer cannot create that code. Keep the original XML for your records and for VAT purposes.
Received an EU e-invoice instead? Peppol BIS, UBL, XRechnung and ZUGFeRD files open in the Peppol invoice viewer.
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Frequently asked questions
Which program opens a KSeF XML invoice?
The KSeF Taxpayer Application, most Polish accounting software, or a browser-based viewer such as the ToolsWebPro KSeF invoice viewer. Any text editor also opens the file, but shows raw XML.
Is a PDF of a KSeF invoice legally valid?
The XML stored in KSeF is the invoice. A PDF or printout is a visualisation. Official visualisations for buyers outside KSeF carry a QR code that links to the invoice in KSeF.
What is the difference between FA(2) and FA(3)?
FA(3) is the logical structure used for KSeF invoices from 1 February 2026. FA(2) was the earlier structure used during the voluntary phase. The namespace in the XML tells you which one a file uses.
Muhammad Saqlain
Cybersecurity Practitioner & Lead EngineerBuilds and tests ToolsWebPro's file converters, invoice viewers and browser-side security tools.
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Open the free tool(s) for this guide — no signup required.
- KSeF Invoice ViewerOpen a Polish KSeF e-invoice XML file (FA(3) or FA(2)) and read seller, buyer, lines, VAT and payment details. Print or save as PDF. Nothing is uploaded.
- Peppol Invoice ViewerOpen supported structured invoice XML, inspect the seller, buyer, line items and totals, then export a readable copy or spreadsheet.
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