ARES: how to look a company up by IČO and check who you are dealing with
Before you issue an invoice or sign up to work with someone, it pays to check their details. In the Czech Republic the place to do that is ARES — the Administrative Register of Economic Entities. This article covers what ARES holds, how to search it, and why the details you copy onto an invoice have to be exactly right.
What ARES is
ARES is an information system run by the Czech Ministry of Finance. It is a public register that pulls together data from several source registers:
- Commercial Register (obchodní rejstřík) — companies, including s.r.o. and a.s.
- Trade Licence Register (živnostenský rejstřík) — individuals and companies holding a živnost, a Czech trade licence
- Register of Economic Entities (RES) — the statistical register kept by the Czech Statistical Office
- Register of VAT payers — who is registered for DPH, Czech value added tax
- other public administration registers
ARES is free and open to anyone. It is the single place to look up basic information about any business registered in the Czech Republic.
What you can find there
Search by IČO or by name and ARES returns:
- IČO — the eight-digit business identification number
- Business name — the registered company name, or the name of the individual trading
- Registered address — the seat or place of business
- Legal form — individual trading under a licence, s.r.o., a.s. and so on
- Date of registration
- DIČ — the tax identification number, where one has been assigned
- Scope of business — the registered trades or fields of activity
- Status — active, in liquidation, or dissolved
How to use it
Through the website
The simplest route is ares.gov.cz. You can search by:
- IČO — the most precise way; it returns exactly one entity
- Name — useful when you do not have the IČO, though it can return several matches
- Address — to find entities registered at a given address
The result is a summary card with the data above, plus links into the source registers where you will find more detail.
Through the API
ARES also publishes a public REST API that applications can query automatically. This is how invoicing and accounting systems fill in company details for you. The API returns structured data in JSON, so the result can be processed without anyone retyping it.
Why the details on an invoice have to be right
An invoice is a tax document and has to carry the details the law requires. Wrong customer details can cost you and your customer:
- An invalid tax document — a customer registered for VAT cannot deduct the VAT on an invoice with incorrect details
- Trouble during an inspection — the tax office may question whether the cost belongs where you put it
- A mismatch in the control statement — if your invoice details do not match what your customer reports in their VAT control statement, the tax administrator may ask both of you about it
- A careless impression — wrong details on an invoice do not read as professional
Right details means: the company name exactly as registered, the correct registered address, a valid IČO, and for VAT payers the correct DIČ.
Filling the details in automatically
Copying data across from the ARES website by hand is slow and easy to get wrong, which is the argument for letting a tool do it.
In Taxorio the ARES lookup runs while you are creating a client:
- Go to Clients and start a new client.
- Enter the partner's IČO.
- Taxorio queries ARES and fills in the business name, the registered address and the DIČ.
- Check what came back and save the client.
That removes the typos, and it keeps your invoices matching the register. Enter a client once and pick them from the list on every later invoice.
Checking whether someone is a VAT payer
Beyond the basic details, you often need to know whether your partner is registered for VAT. Two reasons:
- Issuing the invoice correctly — if the customer is a VAT payer, you put their DIČ on the invoice and show the taxable amount and the VAT separately
- Checking their standing — the Financial Administration publishes a list of unreliable VAT payers. If your supplier is an unreliable payer, or you pay them to an account they have not published, you can become liable for the VAT they fail to pay (§ 109 of the VAT Act) — so it is mainly suppliers worth checking
Where to check a Czech VAT payer
- ARES — shows the DIČ and whether the entity is registered for VAT
- The VAT payer register — on the Financial Administration site, where you can also see the published bank accounts and whether the payer is marked unreliable
- The Financial Administration's mobile app — for a quick check away from the desk
The two sources can disagree for a short time after a change. When Taxorio marks a new client as a VAT payer on the strength of the ARES record, it checks the DIČ against the Financial Administration's register before it does so, rather than trusting a single source.
Checking an EU VAT ID (VIES)
If you trade with partners in other EU member states, you need to confirm that their VAT ID is valid in VIES, the VAT Information Exchange System. That check matters above all when:
- supplying goods to another member state, where the supply is exempt
- supplying services with a place of supply in another member state, under the reverse charge
- completing the EC Sales List
You can run the check on the European Commission site at ec.europa.eu/taxation_customs/vies, or inside Taxorio: enter a client with a foreign VAT ID and Taxorio validates it through VIES and tells you if the number does not check out.
What ARES does not cover
ARES is a good first stop, but it has limits:
- Financial data — ARES holds no financial statements. Those are in the Collection of Deeds of the Commercial Register (justice.cz).
- Beneficial owners — the Register of Beneficial Owners (esm.justice.cz) holds who ultimately owns a company.
- Insolvency — whether an entity is in insolvency proceedings is in the Insolvency Register (isir.justice.cz).
- Enforcement proceedings — the Chamber of Executors publishes these (ceecr.cz).
With a new partner it is worth checking the insolvency register, and for a larger engagement the Collection of Deeds as well. It lowers the odds of invoicing someone who cannot or will not pay.
Practical tips
- Search by IČO whenever you have it — it is the precise identifier, and company names can be very close to one another.
- Look at the status — confirm the entity is active and its registration has not been cancelled.
- Refresh long-standing clients — companies move, rename and change legal form. Check the details on a client you have been invoicing for years.
- Keep a record of the check — being able to show that you verified a partner's details can help during a tax inspection.
Correct details on an invoice are not a formality. They are a statutory requirement and they protect both sides of the transaction. Letting the ARES lookup fill them in saves the time and removes the retyping errors.
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.