01 — The trap with no error message
Its root element is also Invoice
A UBL invoice and an ISDOC invoice both open with an element called
Invoice. A reader that identifies formats by that name treats the
Czech one as UBL — and then there is no error, just a row where everything is
empty: no number, no supplier, no amount.
Here the namespace is checked first (isdoc.cz), and if the export
stripped it, at least two elements that only ISDOC has must be present. One is not
enough — plenty of unrelated documents have a single matching tag.
02 — The field the bank actually uses
Variabilní symbol, not the invoice number
A Czech bank statement matches payments on the variabilní symbol. Reconcile on the invoice number alone and nothing lines up, however carefully the numbers are read.
So it is carried into its own column, alongside the account — IBAN when the file
has one, otherwise the domestic number/bank code pair. IBAN check
digits are recomputed (ISO 13616, mod 97-10), which catches a typo without asking
anyone.
Two dates that are not the same date
ISDOC carries both an issue date and a tax point date (DUZP), and Czech period allocation follows the tax point. They are kept apart: the tax point never overwrites the issue date, and is only used if the issue date is missing.
Collapsing two dates into one column is worse than leaving one empty. An empty cell is visible; a wrong date that looks plausible gets booked.
Advance payments, and totals that legitimately differ
When deposits have been paid, the payable amount is not the tax-inclusive total — and that is correct, not an error. A checker that insists on "net + VAT = total" flags every such invoice. Here that rule is simply not applied in that case: not because it is unimportant, but because it does not hold there.
What else lands in a Czech inbox
The same drop zone reads Peppol UBL and CII, Factur-X and ZUGFeRD PDFs, German
XRechnung, Italian FatturaPA (including signed .p7m), Spanish Facturae,
Polish KSeF, Romanian e-Factura, Austrian ebInterface, Hungarian NAV and Finnish
Finvoice — plus ZIP archives and .eml / .msg emails.
Each one is held against the EN 16931 rules by number where
that standard applies, and where it does not, the compliance column says so instead of
leaving a bare dash.
Trying it
Drop files on the main page — up to 10 invoices per export and 20 a day, free, no account, and the count resets at midnight. Pro lifts both limits for 29 € once, with no renewal.
Nothing is uploaded
The files are read in the browser. There is no server they could go to, and it takes two minutes to confirm: open the developer tools, the Network tab, and drop an invoice in — no request goes out. Or load the page, disconnect the network, and drop it anyway. It still works. Why that check matters.