Korean BRN Validator
Quickly verify a Korean Business Registration Number for invoices and vendor checks. Uses the NTS checksum to flag typos, and decodes the 4th–5th digits into business type.
How to Use
Type the 10-digit BRN. Hyphens are auto-inserted after the 3rd and 5th digits (e.g., 123-45-67890).
Validated by the official NTS algorithm in real time. Invalid or fabricated numbers show a red ✗.
The 4th–5th digits (e.g., 124-86-... → 86) decode into individual / corporation / non-profit / tax-exempt categories.
FAQ
How is the checksum computed?
NTS standard: multiply the first 9 digits by weights [1,3,7,1,3,7,1,3,5], sum them, add floor(digit[8] × 5 / 10), then (10 − sum mod 10) mod 10 must equal the last digit.
What do the 4th–5th digits mean?
NTS classification: 01–79 individual (general/simplified), 80 some non-profits, 81/86/87/88 for-profit corporations, 82 non-profit (schools/religion), 83 government, 84 foreign corporations, 85 unit-tax businesses, 89 unincorporated religious groups, 90–99 tax-exempt individuals.
Can a valid BRN belong to a closed business?
Yes. This tool only validates format. To check if the business is still active, use the National Tax Service's status lookup (home.hometax.go.kr).
Is the BRN sent to a server?
BRN is public information, but this tool sends nothing — validation runs entirely in your browser via JavaScript. No localStorage either.
How does this differ from RRN?
RRN (Resident Registration Number) is a 13-digit personal ID (sensitive). BRN is a 10-digit business ID (public). Different lengths, different algorithms.
