IČO, DIČ and birth number: the Czech identifiers that run your paperwork

Sooner or later a Czech counterparty asks: "What is your IČO?" and then, in the same breath, "And your DIČ?" A foreign founder who has just registered a company often answers with the number printed on the registration certificate and discovers that the second question has a separate answer. Three identifiers do most of the work in Czech paperwork, and each exists for a different reason. Get them straight and invoices, contracts and tax forms stop bouncing back.

The IČO: who you are

The IČO (identifikační číslo osoby) is an eight-digit identifier that marks a legal entity or a self-employed person in the state's registers. The last digit is a check digit calculated from the first seven, which is why a mistyped IČO is usually rejected by a form straight away. A company gets its IČO when it is entered in the commercial register. A sole trader receives one when the trade licensing office registers the business. Associations, foundations, public bodies and branches of foreign firms each have their own entry route, but the logic is the same: the number is issued once, stays with the entity for life and is not reused.

The IČO is public. The state keeps it in the register of persons, one of the basic registers, and anyone can look a company up by it. The Ministry of Finance runs ARES, a free search that pulls together data from the commercial register, the trade licensing register and other sources, and it is the fastest way to confirm that a counterparty exists, has the name and address it claims and is not struck off. Our guide to the commercial register covers the deeper layer.

The DIČ: who you are for tax

The DIČ (daňové identifikační číslo) is the tax identification number. The Financial Administration assigns it after registering the taxpayer. For a company it is almost always "CZ" followed by the IČO. For an individual it is "CZ" followed by the birth number, a nine- or ten-digit number the person already has. A foreign person without a Czech birth number is issued one in the system by the competent authority; our piece on the Czech birth number explains how it comes about.

The "CZ" prefix is an EU convention, a two-letter country code that tells foreign systems which country issued the number. That is why the DIČ doubles as the VAT number on cross-border invoices. And here is the trap.

Why DIČ does not equal VAT payer

A business can hold a DIČ without being a VAT payer. The DIČ identifies you for taxation generally, including income tax. VAT payer status begins on a specific date and is recorded in the register of VAT payers published by the Financial Administration. A small business below the registration threshold may have a DIČ for years and never charge VAT. A foreign customer who sees "CZ12345678" on an invoice should not assume VAT is due, charged or deductible without checking.

The two statuses are separated for a reason. The first is identification, the second is a legal regime. Our explainers on Czech VAT and when to register for VAT cover the second one.

How to verify a business in five minutes

For a Czech counterparty, three free checks cover most of what you need. ARES confirms name, legal form, address and status from the registers. The register of VAT payers on the Financial Administration's portal shows whether the company is a payer, whether it has been declared an "unreliable payer" (nespolehlivý plátce) and which bank accounts it has published for VAT purposes. For an EU counterparty, the Commission's VIES service validates a VAT number across member states.

Pay particular attention to the published bank accounts. A customer who pays a supplier's VAT to an account that is not registered can, in certain cases, become liable for that VAT. That is a reason many Czech accounts-payable teams check the register before a large payment, and a reason to publish your own accounts correctly. See what a valid invoice contains for the details a payer must show.

Where the numbers appear

On an invoice, the supplier's IČO is required, and the DIČ is required if the supplier is a VAT payer. On a contract, the IČO identifies the party far more reliably than a name, because names can be similar. On a Czech tax return, the DIČ is the first thing the form asks for. On a bank form, a customs declaration or a public tender, one of the two is nearly always requested.

Customs uses a third identifier, the EORI number, which businesses need to import or export goods across the EU border. It is issued through the Customs Administration, and our piece on export basics says more.

Individuals, employees and foreigners

An employee has no IČO and no need of one. Tax on a salary is handled by the employer, who identifies the employee by the birth number. A foreigner who starts a business needs the full chain: a trade licence or company registration, then the IČO, then registration with the tax office. Our guides to becoming self-employed and registering an s.r.o. show how this plays out.

Do not confuse these identifiers with the ID of your data box, a separate seven-character code that official letters use, or with an LEI, a global financial identifier needed by some regulated entities. They look similar on a form and do different things.

Typical mistakes

The commonest are small. Writing the DIČ without the CZ prefix on a cross-border invoice. Using an IČO from an old contract after a company has changed its legal form or merged. Sending an invoice to a sole trader's DIČ when the business has moved to an s.r.o. Entering a number with a digit transposed and then wondering why the bank or the tax portal rejects it.

When a company changes its name, address or legal form, the numbers can stay the same or change depending on what happened legally. A merger or a conversion has different consequences from a simple rename. If a counterparty tells you its numbers have changed, ask for the register extract.

Frequently asked questions

Where do I find my own IČO?

On the registration certificate, in the commercial or trade licence register, or by searching your company name in ARES.

Do I need both numbers on an invoice?

The IČO is required. The DIČ is required if you are a VAT payer. Check the invoice rules for the full list.

Is my DIČ the same as my VAT number?

The number is the same, but VAT status is a separate legal state. You are a VAT payer only from the date the Financial Administration records.

Can I look up someone else's numbers?

Yes. Company numbers and VAT payer status are public. Individual birth numbers are not.

Next time a counterparty asks for your numbers, send both, say whether you are a VAT payer, and attach a register extract. It saves a week of back and forth.

This is a general explainer, not legal or tax advice.