Group CZEN

Free tool

Bulk check of Czech company IDs (IČO) in ARES

Paste a column of Czech company IDs (IČO) from Excel. For each one, the tool checks the check digit and fills in the name, registered address, VAT ID (DIČ), company status and VAT registration from ARES, the Czech business registry. You download the result as a CSV. Your browser sends the list of IDs directly to ARES; nothing comes to us.

Try it How to use it

Check Czech company IDs (IČO)

Up to 100 different company IDs at once. Data comes from ARES, the Czech business registry run by the Ministry of Finance.

One IČO per line, or separated by commas, semicolons or tabs. Paste only the column with company IDs.

Where the data goes

Your browser sends the list of company IDs directly to ARES (ares.gov.cz). Nothing comes to us. The tool stores nothing.

What it does not check yet

Unreliable VAT payers and published bank accounts. You can check them by VAT ID in the Czech Financial Administration’s application (in Czech).

VAT Register (Registr DPH)

Data from ARES is for information only and is not an official document.

Result

Nothing checked yet. Paste company IDs or click “Try an example”.

Cleaning up your address book before a switch?

Duplicates, dissolved companies and missing company IDs are better resolved before you move the data to new software.

Switching accounting software

Checking the whole address book

Your whole address book in POHODA, Money, ABRA or Raynet checked against ARES and the VAT register, with a change log for approval.

Data migration and cleansing

How to use the tool

  1. 01

    Paste the company IDs

    One IČO per line, or separated by commas, semicolons or tabs. Just copy the column from Excel. Spaces, a CZ prefix and missing leading zeros are fine.

  2. 02

    Run the check

    The tool first checks the format and the check digit and removes duplicates. Then it sends ARES one request with all valid IDs, at most 100 at a time.

  3. 03

    Review the table

    For each IČO you see the name, registered address, VAT ID, entity status and VAT registration according to ARES. The “Problems only” switch leaves just the rows to look into: dissolved, in liquidation, not found and invalid.

  4. 04

    Download CSV

    Save the result as a CSV for Excel. Company IDs stay as text, including leading zeros. The file is created in your browser.

  5. 05

    Check unreliable payers separately

    This tool does not yet check unreliable VAT payers or published bank accounts. You can find them in the VAT Register (Registr DPH) application of the Czech Financial Administration.

Where the data comes from and what the tool checks

Check digit: the last digit of an IČO is the check digit. The first seven digits are multiplied by the weights 8, 7, 6, 5, 4, 3 and 2, the products are added up and the remainder after dividing by 11 is taken. The check digit is 11 minus the remainder; a result of 10 becomes 0 and 11 becomes 1. Example: for IČO 25596641 the sum is 176, the remainder 0, so the check digit is 1. The tool does not send an IČO with a wrong check digit to ARES at all.

Older company IDs have fewer digits and are padded with leading zeros. Excel likes to strip leading zeros, so the tool pads shorter numbers to eight digits itself and says so in the note.

Company data: the tool calls the public interface (API) of ARES (Administrative Register of Economic Entities) of the Czech Ministry of Finance, the Economic Entities service. No sign-up and no key. It sends all IDs in one request, so it checks at most 100 different IDs at a time.

The tool takes the entity status from the status in the Czech base register of persons, as returned by ARES (active, dissolved). If the entity is not listed there, it uses the status in the primary source, for example the Trade Register. It takes VAT registration from the status of the VAT source in ARES. It recognizes a VAT group member by the group’s VAT ID. ARES may not return a company that has already been deleted from the Commercial Register at all. The tool then shows it as “Not found”, not as dissolved. Always look into IDs that were not found.

What the tool does not check: unreliable VAT payers and published bank accounts. These are kept in the Czech Financial Administration’s register of VAT payers, and its web service cannot be called directly from a browser on another website. You can check them in the VAT Register (Registr DPH) application. It is worth doing for suppliers: under Czech law, if you pay an unreliable VAT payer or pay to an account that is not published in the register, you can, under the conditions of Section 109 of the Czech VAT Act, be liable for tax the supplier does not pay.

According to the terms of use, data from ARES is for information only and is not an official document. The Ministry of Finance reserves the right to restrict users who send more than 500 requests per minute or repeatedly send identical or incorrectly filled-in requests. That is why the tool sends one request per check and removes duplicates and invalid IDs in advance.

Privacy: your browser sends the list of company IDs directly to ARES. Nothing goes to the PackLabs server and the tool stores nothing, not even in your browser.

Sources

Frequently asked questions

How many company IDs can I check at once?
At most 100 different IDs per check. Duplicates and invalid IDs do not count toward the limit. Split a longer list into batches of one hundred and run them one after another, not all at once.
Is my data sent anywhere?
Only the company IDs, and only to ARES run by the Czech Ministry of Finance. Your browser sends them directly. Nothing comes to us, the tool stores nothing and the CSV is created in your browser.
Does the tool detect unreliable VAT payers?
Not yet. Unreliable payers and published bank accounts are kept in the Czech Financial Administration’s register of VAT payers, and its service cannot be called directly from a browser. You can check them in the VAT Register (Registr DPH) application on the Financial Administration website. It is worth doing for suppliers, because under Section 109 of the Czech VAT Act, paying an unreliable payer or to an unpublished account can make you liable for their tax.
Does the tool verify VAT IDs in VIES?
Not yet. The European Commission’s VIES is used to verify VAT IDs of companies from other EU countries in cross-border trade. For Czech companies, ARES already provides the name, address and VAT ID. You can verify foreign VAT IDs on the VIES website.
Can company ID checks run automatically?
Yes. We can build the check against ARES and the VAT register directly into the address book in your accounting software or CRM. For example as a regular check for dissolved companies and unreliable payers, or as a clean-up of the address book before moving to a new system. We start with a free 30-minute audit.

An address book without dissolved companies and duplicates

We check company IDs, VAT IDs and unreliable payers across your whole address book and give you the changes for approval. Before moving to a new system and on an ongoing basis.

Data migration and cleansing Free 30-minute audit

Want this done automatically?

Tell us what you are dealing with. We start with a free 30-minute audit.