Czech & Slovak Company Checker (ARES, VIES, RPO)

What is Czech & Slovak Company Checker?

Czech & Slovak Company Checker takes a list of companies and checks each one against five official registers: ARES, the Slovak RPO, EU VIES, and ADIS, the Czech tax authority's register of VAT payers. All four are free and public. The work is in querying them in bulk, joining them on one company, and dealing with the rows where the name you have does not match the name the register has.

The part nobody else automates is the bank account. Under §109 of the Czech VAT Act, if you pay a supplier into an account that supplier never published with the tax authority, you can be made liable for the VAT that supplier then fails to pay. Those published accounts sit in ADIS. Hardly anyone checks them, because by hand it is one lookup per invoice. Give this actor the account number printed on the invoice and it tells you whether the supplier published that account, and if not, which accounts they did publish.

It also returns unreliable payer status, VAT validity from VIES, and fuzzy name to company ID matching with a confidence score. That last one matters when the supplier list came out of accounting software with names but no IČO. Rows it cannot match are not charged. What it cannot do is tell you an invoice is genuine. It tells you the account on it matches what the supplier declared, which is a narrower thing.

The check nobody else automates

Under §109 of the Czech VAT Act, if you pay a supplier's invoice to a bank account that supplier has not published with the tax authority, you can be held liable for their unpaid VAT. Companies publish those accounts officially, but nobody checks invoices against them, because the data lives in a SOAP service most people never touch.

This actor joins it. Give it a company ID and the account number printed on the invoice:

{ "identifier": "27082440", "bankAccount": "2171532/0800", "reference": "invoice-2026-002" }

and you get back:

{
  "matched": true,
  "identity": { "name": "Alza.cz a.s.", "ico": "27082440", "address": "Jankovcova 1522/53, Holešovice, 17000 Praha 7" },
  "vatValid": true,
  "unreliablePayer": false,
  "publishedAccounts": ["35-3355550267/0100", "2171532/0800", "188505042/0300", "..."],
  "accountMatchesPublished": true,
  "accountChecksumValid": true,
  "riskFlags": []
}

Change one digit in that account number and the answer flips, with the reason spelled out:

{
  "accountMatchesPublished": false,
  "accountChecksumValid": false,
  "riskFlags": [
    "ÚČET NA FAKTUŘE NENÍ MEZI ZVEŘEJNĚNÝMI: platba na nezveřejněný účet zakládá ručení za DPH dodavatele",
    "Číslo účtu neprošlo kontrolní číslicí ČNB"
  ]
}

That is a fraud and liability check on invoice payments, run over a whole supplier list at once.

What gets checked, and where it comes from

Source	What it provides
ARES (Ministry of Finance)	Czech company identity: name, registered address, legal form, NACE codes, VAT number, registration and dissolution dates
RPO (Slovak Statistical Office)	Slovak company identity, including full name and address history
EU VIES	Whether the VAT number is currently valid anywhere in the EU
MFČR ADIS	Unreliable-VAT-payer flag and the officially published bank accounts
ISIR (Ministry of Justice)	Insolvency proceedings: file number, court, status such as bankruptcy or debt relief, start and end dates

Every output row carries a provenance block naming the register, the exact URL queried, and the timestamp, so the result is auditable rather than merely asserted.

Insolvency is checked on every Czech row

Every Czech company is also looked up in ISIR, the official insolvency register. An open proceeding comes back as the first risk flag with the file number, the court, the status (bankruptcy, debt relief, reorganisation) and the date it started, plus a link to the court file. A closed proceeding is reported with its end date, because a supplier that went through bankruptcy three years ago is still worth a second look. An empty answer from the register is a verified "no proceedings", not a missing check.

Input

Give it whatever you have. A company ID, a VAT number, or just a name:

{
  "companies": [
    "45274649",
    { "identifier": "27082440", "bankAccount": "2171532/0800", "reference": "inv-002" },
    { "name": "deriverge s.r.o." }
  ]
}

• Company IDs are checksum-verified locally before any lookup, so a typo costs you nothing.
• Names are resolved with a confidence score. Legal-form suffixes and diacritics are normalised, so NOVÁK SRO, Novák s.r.o. and Novák s. r. o. all match. When two companies match a name almost equally well, the row is flagged for manual review instead of guessed.
• Bank accounts accept both the local format (27-5868650297/0100, leading zeros fine) and Czech IBAN.
• reference is returned unchanged, so you can join results back to your own rows.

Watch a list for changes

Checking a supplier once is useful. Checking the same list every morning and reading only what changed is what keeps you out of trouble. Give the run a watch name (or save it as a task and schedule it) and every later run compares its results with the previous one: a company that turned inactive, a new risk flag, a VAT registration cancelled, a published account that disappeared. The differences are stored in the CHANGES record of the run, ready for an integration or an email. The comparison itself is free.

Pricing

Event	Price
Run fee, charged once per run that resolves at least one company	$0.03
Company successfully matched	$0.006
Each additional register joined (VAT check, payer status, account comparison, insolvency)	$0.002
Company not found	free

A hundred suppliers checked against all four registers cost about $1.03. The German and Swiss equivalents charge $0.81 for the same list and return neither payer reliability nor published bank accounts. Rows you cannot match cost nothing, so a messy supplier list is safe to throw at it, and a run that matches nothing costs nothing at all.

What you get that others skip

• Unmatched companies are free. Invalid company IDs and account numbers are rejected by checksum locally, before any request is spent.
• Every value carries provenance: which register said it, at which URL, and when.
• A payment risk check nobody else automates: the invoice account is compared against the accounts the supplier published with the tax office, because paying an unpublished account creates VAT liability under Section 109 of the Czech VAT Act.
• The whole pipeline runs a live check every morning, so a register changing its format breaks our monitoring, not your run.

Frequently asked questions

What does an unmatched row cost? Nothing. Rows that fail the checksum or cannot be found in any register are returned with an explanation and are never charged.

Where does the data come from? Five official registers: Czech ARES, the Slovak RPO, EU VIES, the Czech insolvency register ISIR and the Czech tax authority's ADIS. All values carry their source and timestamp.

Can I mix IČO, VAT numbers and company names in one list? Yes. Each row is recognised by its shape, and plain names are matched with a confidence score.

What happens when a register is down? The affected fields come back null with a note saying the check could not be performed. A source outage never fails your whole batch.

Typical uses

• Before paying invoices: verify the account on the invoice is the supplier's published one
• Onboarding suppliers or customers: one pass over a CSV of company IDs
• Cleaning a CRM or accounting export: resolve names to company IDs, fill in addresses, drop dissolved companies
• Recurring monitoring: schedule it monthly and watch unreliablePayer and publishedAccounts for changes
• AI agents: call it through MCP; the output schema is declared, so the agent knows the shape before running

What it does not collect

No directors, no owners, no personal names or contact details. Companies only. Insolvency-register data about individuals is deliberately out of scope.

Speed, cost and reliability

All four registers are official, free, and have no anti-bot protection, so runs need no proxy and no browser. Local checksum validation on company IDs and account numbers means malformed rows never reach the network.

When a register changes its response format, the run fails loudly rather than returning rows with silently missing fields.

FAQ

Can I check a company without knowing its ID? Yes: pass name. You get the resolved company plus a matchConfidence, and ambiguous cases are flagged.

What if a company has no published bank accounts? That is itself flagged as a risk. A VAT-registered company that has published none is unusual and worth a question.

Does it work for Slovak companies? Identity yes, via the Slovak business register. The unreliable-payer flag and published accounts are Czech-specific: Slovakia maintains its own separate list, which this actor does not yet cover.

How current is the data? Every query hits the live register at run time; nothing is cached. The provenance block records exactly when each answer was fetched.

Something broke. How fast will it be fixed? Issues are answered within 12 hours.