Business Registration Number Checker
Check whether a Korean business registration number is valid.
Up to 500 lines are checked at once.
Enter a number to see the result here.
Check business status on NTS Hometax ↗
On Hometax, look under the business status lookup menu to see whether a business is active, suspended, or closed.
How the check digit works
A Korean business registration number has 10 digits: a 3-digit tax office code, a 2-digit type code, a 4-digit serial number, and a final check digit calculated from the first nine digits.
Multiply the first nine digits by 1, 3, 7, 1, 3, 7, 1, 3, 5 and add them up, then add the quotient of (ninth digit x 5) / 10. The last digit of (10 minus the sum mod 10) must equal the tenth digit.
Middle two digits (type code)
| Middle digits | Type |
|---|
What this tool cannot tell you
A number that merely satisfies the formula is reported as valid. This tool does not confirm that the number was ever issued or that the business is still operating; use the NTS Hometax business status lookup for that. Numbers are checked in your browser and never stored.