Guide · invoicing
How to issue a compliant invoice in Czechia
An invoice isn't just a piece of paper with an amount — it's a tax document with mandatory fields. Here's everything it must contain, in plain English.
Required fields: non-VAT payer vs VAT payer
Most Czech freelancers invoice as non-VAT payers — their documents need fewer fields. The differences:
| Field | Non-VAT payer | VAT payer |
|---|---|---|
| “Tax document” label | no (“invoice” is fine) | yes |
| Name & registered address of both parties | yes | yes |
| IČO (company ID) of both parties | yes | yes |
| DIČ (VAT ID) of both parties | — | yes |
| Unique document number | yes | yes |
| Issue date | yes | yes |
| DUZP — date of taxable supply | yes | yes |
| Scope and subject of the supply | yes | yes |
| Tax base, VAT rate, tax amount | — | yes |
| Total amount due | yes | yes |
| Payment details (account, variable symbol) | recommended | recommended |
| Due date | recommended | recommended |
VAT payers additionally break the tax down by rate and show unit prices excluding VAT under § 29 of the VAT Act. The document number must be unique either way — a continuous series such as 2026-0042 is the safe pattern.
DUZP: the date that fixes taxation
DUZP is the day goods were delivered or a service performed — not the issue date. For continuous supplies it's the last day of the period; for received advances, the day the payment arrived.
Numbering and due dates
The law requires an unambiguous sequential number. A continuous series — typically year-sequence — is the safest pattern; you may split CZK and EUR series by prefix.
A due date isn't legally required, but without it the client doesn't know when to pay — 14 days is the Czech standard. After it lapses you can charge statutory late-payment interest, so always state it.
Formats: PDF, ISDOC, email
A PDF sent by email is a fully valid tax document. ISDOC (.isdocx XML) additionally carries structured data the recipient's accounting software reads automatically — larger customers and public administration often require it. Invico attaches ISDOC to every invoice automatically, along with a Czech QR payment code.
Frequent mistakes
- Missing DUZP — the most common formal defect on recurring and advance invoices.
- Wrong IČO/DIČ — verify customers in ARES and the VAT register; Invico pre-fills them from ARES.
- Gaps in numbering — a deleted invoice leaves a hole auditors notice. Cancel, don't delete.
- Proforma treated as an invoice — it isn't a tax document; a receipt tax document follows the paid advance.
- No archiving — keep documents 10 years; electronic is fine, retrievability is required.
FAQ
Is a proforma a tax document?
No — it's a payment request. The tax document is issued once the advance arrives.
Can an invoice be just a PDF in an email?
Yes. For automated intake at larger customers, ISDOC helps — Invico generates it automatically.
How long to keep invoices?
10 years from the end of the year of supply. Electronic archiving is sufficient.
Invoices without checking the rules
Invico watches the series, VAT IDs, DUZP and due dates for you — issue a compliant invoice in 60 seconds, with a QR code, ISDOC and a live link for your client.
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