A correctly completed invoice is the foundation of any business. Even experienced people still make mistakes with them — mistakes that get the invoice sent back by the customer, cause trouble in a tax inspection, or attract a penalty. This article goes through what an invoice has to contain, how a tax document differs from an ordinary invoice, and what a properly completed one looks like.
Tax document versus an invoice from a non-payer
Before the individual fields, two kinds of document have to be told apart. Confusing them is a common source of misunderstanding.
Tax document (VAT payer)
If you are registered for DPH (daň z přidané hodnoty, Czech VAT), what you issue is not merely an invoice but a tax document (daňový doklad). It is subject to the requirements of the VAT Act (Act No. 235/2004 Coll.), whose particulars are listed in Section 29. The tax document is what lets your customer claim an input VAT deduction, so getting the details right matters to both sides.
Invoice from a VAT non-payer
If you are not registered for VAT, you issue an ordinary invoice (or a receipt). The requirements here are lighter and follow mainly from the Civil Code and the Accounting Act. The document must not show VAT, because you have no right to charge it. Adding the line "Nejsem plátce DPH" ("I am not registered for VAT") removes any doubt.
Particulars of a tax document under Section 29 of the VAT Act
Section 29 sets out the mandatory particulars of a tax document. If one of them is missing, the customer's VAT deduction becomes harder to defend — the entitlement can still be proved by other means (Section 73(5) of the VAT Act), but it complicates matters.
1. Marking the document
Section 29 does not prescribe a heading, but in Czech practice a tax document is marked "Faktura – daňový doklad" ("Invoice – tax document"). It costs nothing and it tells the customer's bookkeeper at a glance what they are holding.
2. Registration number of the document
Every tax document needs a unique registration number that identifies it, and the numbers must form an unbroken series. The most common format combines the year with a sequence number — 20260001, 20260002 and so on. In Taxorio the number is generated automatically in a fixed YYYYXXXX format, so there is nothing to keep track of by hand.
3. Date of issue
The day the tax document was issued. It matters, among other things, because a VAT payer has to issue the tax document within 15 days of the date of the taxable supply.
4. Date of taxable supply (DUZP)
DUZP (datum uskutečnění zdanitelného plnění, the date of the taxable supply) is one of the most important fields on an invoice and the one most often forgotten. It decides which tax period the transaction falls into. The date of issue and the DUZP can differ — a service finished on 28 January, an invoice issued on 3 February. The DUZP is then January, and the VAT is declared for January.
5. Supplier details
The invoice must carry the supplier's full details:
- Business name (for an individual, first name and surname)
- Registered seat (for an individual, the place of business)
- DIČ (daňové identifikační číslo, the tax identification number)
- IČO (identifikační číslo osoby, the business identification number)
6. Customer details
The same applies to the customer:
- Business name, or first name and surname
- Registered seat or address
- DIČ — required if the customer is registered for VAT
- IČO
7. Description of the supply
The invoice must contain a sufficiently specific description of what was delivered or provided. A vague "services" or "consulting" is not enough. Something like "Website development under the contract of 5 January 2026" or "Graphic design of the logo and visual identity" is.
8. Taxable amount
The amount for the goods or services excluding VAT. If the invoice contains items at different VAT rates, the taxable amount has to be shown separately for each rate.
9. VAT rate
Two VAT rates apply in Czechia in 2026:
- 21 % — standard rate (most goods and services)
- 12 % — reduced rate (food, books, accommodation, construction work on housing and other items listed in the Act)
10. Amount of VAT
The VAT in crowns. Again, where the invoice mixes rates, the VAT has to be worked out for each rate separately.
11. Total amount
The total payable including VAT. On a mixed-rate invoice this is the sum across all rates.
What a non-payer's invoice must contain
If you are not registered for VAT, the requirements are simpler. The invoice must show:
- First name and surname (or business name)
- IČO
- Address of the place of business
- Registration number of the document
- Description of the supply (what was delivered or provided)
- Date of issue
- Total amount
A non-payer's invoice must not show VAT. We recommend adding "Nejsem plátce DPH" or "Není plátce DPH dle zákona č. 235/2004 Sb." ("Not registered for VAT under Act No. 235/2004 Coll.").
A worked example
Here is a fictional example of a correctly completed invoice from a VAT payer:
FAKTURA – DAŇOVÝ DOKLAD (Invoice – tax document) No. 20260015
Supplier: Jan Novák, IČO: 12345678, DIČ: CZ8501011234, Příčná 5, 110 00 Praha 1
Customer: Vzorová firma s.r.o., IČO: 98765432, DIČ: CZ98765432, Vinohradská 100, 120 00 Praha 2
Date of issue: 20. 1. 2026
Date of taxable supply (DUZP): 17. 1. 2026
Due date: 3. 2. 2026
Payment method: Bank transfer
Bank account: 1234567890/0100
–
Item: Responsive web design under the contract of 2. 1. 2026
Quantity: 1 pc | Unit price: 45 000 Kč
Taxable amount: 45 000 Kč
VAT 21 %: 9 450 Kč
Total payable: 54 450 Kč
Note that the DUZP (17 January) differs from the date of issue (20 January) — the work was finished and handed over before the invoice went out. The VAT on this invoice falls into the January 2026 tax period.
The most common mistakes
- Missing DUZP — the most frequent one of all. Without a DUZP the tax document is not valid.
- Missing or wrong DIČ — where the customer is registered for VAT, the DIČ has to be there. A wrong one blocks their deduction.
- A vague description — "work" or "services" is not enough. The tax office can challenge a document like that.
- The wrong VAT rate — mixing up the standard and reduced rates is common in construction work and some services.
- Arithmetic that does not add up — the taxable amount, the rate and the total have to agree.
- A broken number series — invoice numbers must form an unbroken series within the period.
How Taxorio takes the work out of it
Filling in every mandatory field by hand is slow and easy to get wrong. Taxorio handles most of it:
- Automatic numbering — invoice numbers are generated in a fixed YYYYXXXX format, so the automatic series has no duplicates or gaps; if you adjust the counter or type your own number, you keep an eye on the series yourself.
- ARES lookup — enter the customer's IČO and Taxorio fills in the business name, address, DIČ and the rest from the ARES register. Nothing to copy off a website.
- DUZP prefilled — when you create an invoice the DUZP is set to the date of issue. If the real one is different, you change it in its own field.
- VAT calculated for you — enter the unit price and the rate and Taxorio works out the taxable amount, the VAT and the total.
- QR payment code — once you switch QR payments on in settings, invoices with a positive amount carry a QR code in the SPD format, which lets the customer pay from mobile banking.
- Three PDF designs — Aurora (a card layout with a strong header), Modern (colour-led) or Classic (plain and structured), whichever suits you.
- Invoice statuses — every invoice moves through Draft, Issued, Paid, Overdue or Cancelled, so you always know where it stands.
Practical tips
- Issue the invoice as soon as the work is done — ideally on the day of delivery. The DUZP is then the same as the date of issue and there is nothing to confuse.
- Save the details of regular customers — in Taxorio you pick the client from the list and everything is prefilled.
- Check the customer's DIČ — for EU customers you can run a VIES check directly in Taxorio.
- Keep invoices for 10 years — the statutory retention period for tax documents is 10 years from the end of the tax period.
- Use price list items — if you invoice the same services repeatedly, save them in the price list in Taxorio and add them to an invoice in one click.
A correctly completed invoice protects you as much as it protects your customer. If you want the whole process of issuing one, step by step, read our guide on how to issue an invoice as a sole trader. Try Taxorio for free — the free plan covers 2 invoices a month.
Taxorio scope: Taxorio provides invoicing and income/expense records for Czech sole traders. It is not full accounting or personalised tax advice. For an unsupported or unusual case, verify the treatment with a Czech accountant or tax adviser before filing.