[Korea] Business Registration Number Check (KR)
Business Registration Number Check (KR) — runs in your browser. Inputs are not stored.
Business registration number check (Checksum only · for reference)
Enter values, then press Calculate.
※ Checksum only. Not a National Tax Service (Korea) lookup of existence or business status. For reference.
How to use
- Enter a 10-digit business registration number (Korea). Hyphens are stripped to digits. The default example is 120-81-47521.
- If the digit count is not 10, you get a length error. 9- and 11-digit values do not pass.
- Press Validate for checksum match and a normalized hyphenated form.
- Valid (checksum OK) only means the format checksum matches—not that a real business exists or is active/closed.
- Reset restores the example number. The NTS Hometax lookup API is not called.
Key concepts
Business registration number validation is a quick checksum filter for Korea’s 10-digit business registration number, including hyphenated forms. The first 9 digits are weighted, summed, and compared with the last digit. This screen runs only that formula in the browser. Use it to screen a 10-digit number (with hyphens) before a Hometax lookup.
It does not look up NTS business status, tax type, closure, or tax-exempt vs taxable. A matching checksum can still be unused or closed; a mismatch suggests a typo. Paste a number from a tax invoice or business card to filter format only. Results are for reference and may differ from administrative records and notices.
Example
Validating the default 120-81-47521 gathers 10 digits, the checksum matches (checksum OK), and the normalized form 120-81-47521 is shown. Changing only the last digit to 120-81-47522 yields a checksum mismatch. Nine digits such as 123-45-678 is a length error. 1208147521 without hyphens gives the same valid result. Confirm existence separately in Hometax. Calculating with on-screen defaults should match the first example. Change the field and calculate again under the same rules. For filings, pay, and contracts, official notices and agreements take priority. These figures are for reference.
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Frequently asked questions
If the business registration number is valid, is it a real business?
No. It only means length and checksum match. Existence and open/closed status need an NTS lookup. For reference only.
Does it look up whether the business is closed?
No. This tool is an offline checksum only. Use Hometax or Gov.kr. For reference only.
Can I enter hyphens in the business number?
Yes. Only digits are extracted. 120-81-47521 and 1208147521 are the same.
Does it tell corporation vs individual businesses apart?
You can sometimes guess from the numbering scheme, but this tool only shows the checksum. For reference only.
Is the business number sent to a server?
No. Validation runs only in the browser. The entered number is not transmitted.
What if business-number validation shows an error?
Suspect a typo or a wrong number. For reference only; it may differ from notices and administrative data.
Last reviewed: 2026-09-04