Slovakia IČO validator
How the IČO format works
- Format
- 8 digits with a weighted mod-11 check digit
- Example
- 31322832
Things to watch for
- Slovakia kept the Czechoslovak IČO scheme after 1993, so the check digit is calculated exactly as for Czech IČOs
- Unlike in the Czech Republic, the Slovak VAT number (IČ DPH) is not built from the IČO — it is SK plus a separate 10-digit tax number
- Checksum only — a pass doesn't confirm the business is registered or active
^[0-9]{8}$IČO (identifikačné číslo organizácie) is the 8-digit organisation number that Slovak companies, sole traders (živnostníci), public bodies and non-profits use to identify themselves in contracts, invoices and public registers. Slovakia kept the scheme when Czechoslovakia split on 1 January 1993, so its check digit is still calculated exactly as in the Czech Republic. Most of what surrounds the number is different, though.
Three numbers on a Slovak invoice
A VAT-registered Slovak business usually shows three separate identifiers:
- IČO: the 8-digit organisation number this tool checks.
- DIČ: a 10-digit tax identification number issued by the Financial Administration (Finančná správa).
- IČ DPH: the VAT number, normally SK followed by the DIČ rather than the IČO. You can check it with the Slovakia VAT number validator.
This is the main practical difference from Czechia, where a company’s VAT number is usually CZ followed by its IČO. In Slovakia you can’t get from an IČO to a VAT number.
The check digit, step by step
Weights 8, 7, 6, 5, 4, 3 and 2 multiply the first seven digits, and the products are added and divided by 11. A remainder of r gives a check digit of 11 − r, except at the edges: a remainder of 0 gives 1, and a remainder of 1 gives 0. For the example 31322832, the weighted sum is 97, the remainder is 9, and the check digit is 2.
What a pass doesn’t tell you
The Czech and Slovak schemes are identical, so a valid checksum can’t tell you which country issued a number, or whether it was issued at all. Confirm the entity in the Slovak Business Register (ORSR). For sole traders, use the trade register (živnostenský register).
Scope: Slovak IČO format and checksum validation only. It doesn’t cover register, tax or VAT status.
Content last reviewed 2026-10-11.
IČO FAQ
Can I turn a Slovak IČO into a VAT number by adding SK?
No. That works for most Czech companies but not in Slovakia. The Slovak VAT number (IČ DPH) is SK followed by a separate 10-digit tax number, so it can't be worked out from the IČO. Get it from the business itself or a public register.
Is a Slovak IČO validated differently from a Czech one?
No. Both countries kept the Czechoslovak scheme after 1993: eight digits, weights 8 down to 2 on the first seven, and a mod-11 check digit. A number that passes here would pass on the Czech page too. Only the registers and the tax numbers around it differ.
Does every Slovak business have an IČ DPH as well as an IČO?
No. A business or organisation gets an IČO when it's registered, but it only gets an IČ DPH once it registers for VAT. Smaller businesses that never register for VAT have an IČO but no IČ DPH.