How to issue an invoice to a US company in KSeF
Check what data to collect from a US counterparty, how to approach VAT, FA(3) XML, the KSeF number and a readable English version.
International invoicesJuly 7, 2026
News
Practical knowledge on KSeF - from integration basics to AI-driven invoice automation. Written from real deployments, not theory.
Articles and instructions
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How to Issue a Final Invoice After an Advance in KSeF
Learn when a final invoice is needed after an advance, how to deduct earlier payments and avoid settling the same sale twice.
GuideJuly 6, 2026
From LiveKid to KSeF: PDF invoices and settlements
LiveKid provides a PDF invoice, PDF correction and settlement, but does not send them to KSeF. See how to turn a PDF into FA(3) XML and submit the invoice to KSeF.
Practice2 July 2026
How to check invoice status in KSeF after submission?
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.
GuideJuly 2, 2026
How to issue a VAT invoice in KSeF step by step
Follow the regular sales invoice process in KSeF: document type, invoice data, XML FA(3), validation, submission, KSeF number, and UPO.
GuideJuly 1, 2026
Invoice Types in KSeF: VAT, KOR, ZAL, ROZ and UPR
Learn how FA(3) identifies standard, corrective, advance, settlement and simplified invoices, and how to choose the right type before submitting it to KSeF.
GuideJune 30, 2026
KSeF and VAT Margin: How to Issue a Margin Invoice
How to record a VAT margin invoice in FA(3): Articles 119 and 120, P_PMarzy, P_13_11, MR_T, MR_UZ and pre-submission checks.
GuideJune 29, 2026
Advance Invoices in KSeF for Small Businesses
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.
GuideJune 24, 2026
KSeF number on an invoice: where to find it and what to store
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.
GuideJune 24, 2026
KSeF for freelancers and sole proprietors: B2B invoices, costs and obligations
When to issue B2B invoices, how to receive costs, track UPO, KSeF number and accountant collaboration.
GuideJune 22, 2026
7 PDF-to-XML KSeF Conversion Errors
Learn the most common errors when converting a PDF invoice to FA(3) XML, their effects in KSeF and how to catch them before submission.
GuideJune 21, 2026
Missing UPO in KSeF: how to download the official receipt?
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.
GuideJune 19, 2026
Frequently asked questions (FAQ)
Short answers about the KSeFGPT app and about the National e-Invoice System itself, with links to the full articles.
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