What is ISDOC?

ISDOC is the Czech national standard for electronic invoices. It was developed in 2008 by the Czech ICT industry association (ICT UNIE / SPIS) as a unified format that Czech businesses and accounting software vendors could agree on. Most major Czech accounting and ERP systems support it natively – Pohoda, Money S3, Helios, ABRA, Premier, and others.

ISDOC files come in two extensions:

• .isdoc — a plain XML file containing the invoice data
• .isdocx — a ZIP archive containing the XML plus any attachments (PDF copies, contracts, etc.)

The viewer opens both. For .isdocx files, drop the archive directly — the viewer extracts the inner XML automatically.

ISDOC versions

The format has gone through several revisions:

• ISDOC 5.x — earlier versions, still encountered in older archives
• ISDOC 6.0.1 — the current stable version, used by most modern software

This viewer reads both. The current ISDOC 6 schema is what almost all production systems output now, so you’re most likely to encounter files using namespace http://isdoc.cz/namespace/2013.

Where ISDOC fits versus Peppol

The Czech Republic, like other EU member states, is gradually adopting Peppol BIS Billing 3.0 for public sector and cross-border e-invoicing under EU mandates. ISDOC remains widely used domestically, particularly between Czech businesses using Czech accounting software. But the long-term direction is mixed: ISDOC for many domestic flows, Peppol for cross-border and public procurement.

If you’re working with both formats, the same viewer handles both — drop in an ISDOC file or a Peppol XML and it detects the format automatically.

When you might need this

• You’re a Czech accountant and a client forwarded you an .isdoc file from a supplier that you want to check before importing
• You’re testing exports from your accounting software and want to confirm the ISDOC file produced is what you expect
• You’re a developer integrating ISDOC import or export into a system and need a quick way to inspect generated files
• You’re working with a Czech vendor from outside the Czech Republic and received an ISDOC invoice that your local tools don’t recognize

What the viewer shows

Standard invoice information, rendered as a normal-looking document:

• Invoice number, issue date, tax point date, due date
• Supplier and customer: name, address, registration number, VAT ID, contact details
• Line items with quantities, unit prices, and VAT rates
• VAT breakdown by rate: typically 21%, 12%, and 0% under current Czech rates
• Subtotal, VAT total, and total payable
• Payment details: IBAN, BIC, bank account in Czech format (account number / bank code), and the all-important variable symbol (variabilní symbol) for payment matching
• Any attachments embedded in the .isdocx archive

Czech-specific fields like the variable symbol and the company registration number and VAT ID pair are preserved and labeled clearly.

Is it safe?

Yes. All parsing happens in your browser via JavaScript. No file or contents are uploaded, logged, or transmitted. Open your browser’s developer tools and watch the Network tab while loading a file — you’ll see nothing carrying the file data.

For Czech accountants in particular, this matters: invoices contain bank details, customer relationships, prices, and other commercially sensitive information that you can’t reasonably hand over to a random web service.

Frequently asked questions

What’s the difference between .isdoc and .isdocx?

.isdoc is just the XML file by itself. .isdocx is a ZIP archive that contains the XML plus any attached files — typically a PDF copy of the invoice for human reading, but sometimes contracts, photos, or other supporting documents. From an accounting data perspective both contain identical invoice information. The .isdocx format is more common in practice because it travels well as a single file.

Which Czech accounting software produces ISDOC?

Most of them. Pohoda (Stormware), Money S3 (Cígler Software / Solitea), Helios (Asseco), ABRA, Premier System, FlexiBee, iDoklad, and many others support ISDOC import and export to varying degrees. The exact features vary — some support only invoices, others handle credit notes, advance payments, and more document types.

Does ISDOC validate or just display?

This viewer only displays. It doesn’t validate the file against the ISDOC schema or check whether the VAT calculations add up. For schema validation, you’d typically use tools provided by ICT UNIE or your accounting software’s built-in import validation.

Will ISDOC be replaced by Peppol?

It’s coexisting with Peppol rather than being replaced outright. Czech public procurement is moving toward Peppol BIS for cross-border interoperability under EU mandates, but domestic B2B exchange in ISDOC continues to be the norm where both parties use Czech accounting software that supports it. Most software vendors support both formats now.

Can I convert ISDOC to PDF here?

Yes — once the invoice is open in the viewer, use your browser’s Print function (Ctrl+P / Cmd+P) and choose “Save as PDF” as the destination. The print stylesheet hides the toolbar and CTAs, so you get a clean PDF of just the invoice.

Does this work without Czech locale settings?

Yes. The viewer renders ISDOC files identically regardless of your computer’s locale. The labels in the viewer follow the language parameter (?lang=en, ?lang=cs, ?lang=de), and Czech-specific fields like variable symbol are labeled correctly in all three.

Related tools

• Peppol invoice viewer: same tool with Peppol-specific context and FAQ
• UBL invoice viewer: for generic UBL 2.1 files including non-Peppol UBL

About this tool

This viewer is built and maintained by Verifical — a document exchange platform for accountants and their business clients, with deep support for the Czech market. ISDOC is a first-class format on our platform, alongside Peppol/UBL and PDF.

If you’re a Czech accountant receiving documents from many clients, our main platform handles ISDOC ingestion, archival, and export to your accounting software automatically — Pohoda, Money S3, and others.