Guide

You sent an invoice to KSeF, but you do not know whether it has been accepted, is still being processed, or was rejected? Check the status, reference number, KSeF number and UPO step by step.

Follow the regular sales invoice process in KSeF: document type, invoice data, XML FA(3), validation, submission, KSeF number, and UPO.

How to handle an advance payment in FA(3), when a settlement invoice is needed, and how to keep the KSeF number, UPO and corrections connected.

Learn what the KSeF number is, how it differs from the P_2 invoice number, where to find it and how to use it in UPO, JPK and payments.

When to issue B2B invoices, how to receive costs, track UPO, KSeF number and accountant collaboration.

Cannot see UPO after submitting an invoice to KSeF? Check status, KSeF number, session, rejection errors and UPO download paths in the app, API or KSeFGPT.

A practical guide for small businesses, sole proprietors and microbusinesses: KSeF deadlines, purchase invoice receipt, UPO, KSeF number, XML FA(3), official MF tools and KSeFGPT.

Not every PDF to XML converter is suitable for KSeF. Check when to choose KSeFGPT, the Taxpayer Application, an ERP, ksefpdf.pl or another tool, and why regular XML from a PDF is not enough.

Find out why KSeF rejected an invoice, how to read its status, correct P_1, FA(3) XML, permissions or a duplicate, and safely submit it again.

An up-to-date guide to the KSeF 2.0 Taxpayer Application: choosing a certificate purpose, generating the private .key file, downloading the .crt file, and securely preparing the complete set for use.

A practical guide for companies that want to move customers and contractors from an old system, Excel, CSV or Fakturownia.pl before KSeF go-live without carrying over duplicates and errors.