Invoice Requirements 2026: What Must Be Included

Do you issue invoices as an OSVČ and aren't sure whether they include all the legally required information? A missing item on an invoice can lead not only to problems with your client, but also to penalties from the tax authority. In this article, we'll walk you through everything an invoice must contain in 2026 and highlight the most common mistakes business owners make.

What Is an Invoice and What Laws Govern It

An invoice is a tax document that serves as confirmation of a completed business transaction between a supplier and a customer. In Czech law, invoicing is governed primarily by two key pieces of legislation:

• Act No. 235/2004 Coll., on Value Added Tax (the VAT Act) — governs the requirements for tax documents issued by VAT payers
• Act No. 89/2012 Coll., the Civil Code — sets out general requirements for commercial documents

Mandatory Invoice Requirements for Non-VAT Payers

If you are not a VAT payer (and most new OSVČ aren't), your invoice must include the following information:

Supplier Identification Details

• First and last name (for OSVČ) or company trading name
• Registered office or place of business — full address including postcode
• Company registration number (IČO)
• If you are registered in the Commercial Register, also include the file reference and the relevant court

Customer Identification Details

• First and last name or company trading name
• Registered office or place of business
• Company registration number (IČO) (if the customer is a business)

Invoice Details

• Invoice number — must form a clear, sequential numbering series
• Date of issue
• Date of supply (or date of payment receipt, if different from the date of issue)
• Due date — not legally required, but standard practice

Description of the Supply

• Precise description of the goods supplied or services rendered
• Quantity and unit of measurement (where applicable)
• Unit price
• Total amount due

Payment Details

• Supplier's bank account number
• Variable symbol (typically the invoice number)
• Payment method (bank transfer, cash, etc.)

Mandatory Invoice Requirements for VAT Payers

For VAT payers, the requirements are stricter. In addition to all of the above, a tax document must include the following under Section 29 of the VAT Act:

Additional Mandatory Details

• Supplier's tax identification number (DIČ)
• Customer's DIČ (if the customer is a VAT payer)
• Tax base — the amount excluding VAT
• VAT rate — in 2026, the applicable rates are 12% (reduced) and 21% (standard)
• VAT amount — stated in crowns and hellers
• Total amount including VAT

Special VAT Schemes on Invoices

In certain situations, you must indicate on the invoice that a special VAT scheme applies:

• Reverse charge — Section 92a of the VAT Act. The invoice must state "the customer is liable to pay the tax"
• Special scheme for travel services — Section 89 of the VAT Act
• Special scheme for dealers in second-hand goods — Section 90 of the VAT Act

Simplified Tax Document

Under certain conditions, the VAT Act allows the issuance of a simplified tax document. This is typically used for smaller transactions.

When a Simplified Document Can Be Issued

• The total amount including VAT does not exceed 10,000 CZK
• It does not involve the supply of goods to another EU member state
• It does not involve distance selling with the place of supply in the Czech Republic
• It does not involve a supply where the recipient is required to declare the tax

What a Simplified Document Does Not Need to Include

• Customer identification details (name, address, DIČ)
• Tax base and VAT amount (it is sufficient to state the total amount and the VAT rate)

Invoice Numbering: How to Number Correctly

Proper invoice numbering is one of the most important organisational aspects of invoicing. The law requires that numbers form a clear and identifiable sequential series.

Recommended Numbering Formats

• Simple sequential series: 001, 002, 003...
• With year prefix: 2026001, 2026002...
• With separator: 2026-001, 2026-002...
• With type designation: FV2026001 (issued), FP2026001 (received)

The Most Common Invoice Mistakes

Based on real-world experience, we've identified the most frequent mistakes business owners make on their invoices:

1. Missing or Incorrect IČO/DIČ

A typo in the IČO or DIČ can mean the invoice is not accepted as a tax document. Always verify details in the ARES system (Administrative Register of Economic Entities) on the Ministry of Finance website.

2. Incorrect Date of Taxable Supply

The date of supply is critical for VAT payers, as it determines which tax period the transaction falls into. It is not the same as the date of issue or the date the goods were delivered.

3. Vague Description of Supply

Descriptions such as "services as agreed" or "consultation" are not sufficient. The description must be specific enough to make it clear exactly what was supplied.

4. Missing Information on the VAT Scheme

If the transaction is subject to the reverse charge mechanism or another special scheme, this must be explicitly stated on the invoice.

5. Incorrect VAT Rate

Using the wrong VAT rate is a serious error. Always check the current rates on the Financial Administration portal (financnisprava.gov.cz).

6. Invoice Without a Number or With a Duplicate Number

Every invoice must have a unique number. Duplicate numbers can cause problems during a tax authority audit.

7. No Indication of Non-VAT Payer Status

If you are not a VAT payer and fail to state this on the invoice, the customer may incorrectly assume that the price includes VAT and request that it be itemised.

Penalties for Incorrectly Issued Invoices

The tax authority can impose fines for errors on invoices. What penalties are at stake?

Penalties for VAT Payers

• For failing to issue a tax document: a fine of up to 500,000 CZK
• For issuing a document with incorrect information: a fine of up to 500,000 CZK
• For failing to submit a control statement (which is based on invoices): 1,000 CZK for late submission, up to 50,000 CZK for non-submission

Penalties for Non-VAT Payers

For non-VAT payers, direct penalties for invoice errors are less severe, but:

• The invoice may not be recognised as an accounting document
• During a tax audit, expenses supported by defective invoices may be challenged
• The customer may reject the invoice and request a corrected version

Corrective Tax Document (Credit Note)

If you discover an error on an invoice you have already issued, you need to issue a corrective tax document. In practice, this is also known as a credit note (if it reduces the original amount) or a debit note (if it increases it).

When to Issue a Corrective Document

• A change in the tax base after the supply has taken place
• Return of goods
• A discount granted after the invoice was issued
• Correction of incorrect information on the original document

Requirements for a Corrective Document

A corrective tax document must include:

• A reference to the original invoice (its number)
• The reason for the correction
• The difference between the original and corrected amounts
• All standard tax document requirements

Electronic Invoicing in 2026

Electronic invoicing is becoming the norm. In 2026, it remains the case that an electronic invoice carries the same legal validity as a paper one, provided that the following are ensured:

• Authenticity of origin — the recipient can verify the identity of the sender
• Integrity of content — the content of the invoice has not been altered since it was issued
• Legibility — the invoice is legible from the moment of issue until the end of the archiving period

Invoicing in a Foreign Currency

If you invoice foreign clients, specific rules apply:

• The amount must be converted to Czech crowns for VAT purposes
• Use the Czech National Bank exchange rate valid on the date of the taxable supply
• State both the amount in the foreign currency and the CZK conversion on the invoice
• VAT payers are required to state the tax base and VAT amount in CZK

Practical Checklist: Review Your Invoice Before Sending

How DokladBot Makes Invoicing Easier

Manually checking every requirement on every invoice is time-consuming and error-prone. DokladBot is an AI accounting assistant available via WhatsApp that can help you:

• Automatically review received invoices and flag any missing requirements
• Record documents effortlessly — simply take a photo of the invoice and send it via WhatsApp
• Track due dates for payments and tax obligations
• Get VAT guidance — correct rates, reverse charge rules, and more

Stop worrying about whether your invoices include everything they should. Leave it to AI.

Try DokladBot for free at dokladbot.cz

Frequently Asked Questions (FAQ)

Does an invoice need to include a stamp and signature?

No. A stamp and signature are not legally required elements of an invoice. Their presence or absence has no bearing on the document's validity. That said, many customers do request them — this is a matter of business custom, not a legal requirement.

What is the difference between an invoice and a tax document?

"Invoice" is a general commercial term. "Tax document" is a term from the VAT Act and applies only to documents issued by VAT payers. Every tax document is an invoice, but not every invoice is a tax document (for example, an invoice issued by a non-VAT payer).

How long do I have to issue an invoice?

A VAT payer must issue a tax document within 15 days of the date of the taxable supply. For non-VAT payers, the law does not specify a deadline, but it is good practice to issue the invoice as soon as possible.

Can I issue an invoice without the customer's IČO?

Yes, if the customer is a private individual who is not a business (a consumer). In that case, a name and address are sufficient. If the customer is a business, their IČO should be included on the invoice.

What should I do if a customer doesn't pay an invoice by the due date?

Start by sending a payment reminder. If the customer still doesn't pay, you can pursue the debt through the courts or hand the receivable over to a debt collection agency. For VAT payers, if a receivable remains unpaid for more than 6 months, the VAT amount may — under certain conditions — be corrected (known as a correction for bad debts).

Is it mandatory to include a due date on an invoice?

The VAT Act does not list a due date as a mandatory requirement for a tax document. However, from the perspective of the Civil Code and good business practice, it is standard and strongly recommended. Without a due date, the statutory payment term of 30 days applies.

Can I issue an invoice retroactively?

Yes, retroactive invoicing is permitted. The key requirement is that the date of the taxable supply must accurately reflect when the supply actually took place. For VAT payers, the document must be issued within 15 days of the date of taxable supply.