A practical guide for businesses and accounting teams: where to find incoming invoices in KSeF, when they are considered received, how often to check them and what to do after retrieval.
Learn how to distinguish a wrong NIP from a suspected scam invoice, when to contact the seller, when to request a correction and how to report abuse in the KSeF 2.0 Taxpayer Application.
Check whether the issue is your phone, login, permissions or KSeF availability. See safe steps and fallback options.
Check when a KSeF invoice is deemed received, how to distinguish the issue date from the KSeF number date and why the payment term still follows from the contract and commercial transaction rules.
A practical guide: how to prepare an XLSX sheet, map columns to FA(3) fields, check errors and send valid invoices to KSeF in KSeFGPT.
Learn what UPO means in KSeF, what it contains, when it can be downloaded, how it differs from the KSeF number and why the Polish official term is Urzędowe Poświadczenie Odbioru.
Free invoice submission to KSeF in 2026: Taxpayer Application KSeF 2.0, e-mikrofirma, KSeF mobile app, KSeFGPT public free tools and a hybrid workflow.
Correction to zero, manual line-item editing, correction from XML and correction from the KSeF invoice list. See how to prepare a corrective invoice in KSeFGPT.
Free PDF to XML KSeF converter - just an email address. Step by step: how to turn a PDF invoice into FA(3) and submit it to KSeF in 2026.
How long do you have to send an invoice to KSeF? Deadlines in online, offline24, unavailability and failure modes. Specific days and legal basis 2026.
How to mass-send invoices to KSeF: batch sessions, CSV structure, FA(3) mapping, validation, and bulk import with KSeFGPT.
How to submit invoices to KSeF in 2026: modes (online, offline24, unavailability, failure), authentication, UPO, limits, common errors and free tools.