Korean BRN Validator Standard NTS checksum

Validate any Korean Business Registration Number (BRN) in seconds. Checksum + business type auto-detection — no login, no API, runs entirely in your browser.

BRN ≠ Corporate Registration Number — they are different

BRN — Business Registration Number

XXX-XX-XXXXX (10 digits)

Issued by the National Tax Service. For tax filings, invoices, B2B transactions. Validated by this tool.

법인등록번호 — Corporate Registration Number

XXXXXX-XXXXXXX (13 digits)

Issued by district court registries when a corporation is incorporated. For registry, contracts, legal identity. Different number — not validated here.

→ Use Corp Reg Number Validator

Business Registration Number (10 digits)

0 / 10 digits Enter a Business Registration Number

Awaiting input

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※ Validated 100% client-side — no server transmission. Sharing the URL leaves the BRN in browser history; share with care.

Type code reference (digits 4–5)

01–79 — Individual taxable business (general/simplified)
80 — Multi-level sales / apartment management offices, etc.
81 / 86 / 87 / 88 — Profit corporation (HQ)
82 — Non-profit corporation (HQ/branch)
83 — Government / municipality / public body
84 — Foreign corporation (Korean branch / liaison)
85 — Profit corporation (branch)
89 — Religious organization (non-incorporated)
90–99 — Tax-exempt individual business

※ Cross-checked against NTS Q&A, Toss Payments developer center, MoneyPin guide (2026-05).

How the checksum works

Strip non-digits to get d[0..9].
With weights W = [1, 3, 7, 1, 3, 7, 1, 3, 5], compute S = Σ d[i] × W[i] for i=0..8.
Add Korea-specific correction floor(d[8] × 5 / 10) to S. Most common implementation bug — easy to miss.
Expected check digit check = (10 − S mod 10) mod 10.
If check === d[9], the BRN is format-valid.

Verified sources: lesstif PHP gist (Korean standard), Toss Payments developer center, MoneyPin guide. PHP/JS/Python implementations cross-checked.

📌 Official Sources · References

Korea National Law Information Center — Value-Added Tax Act Enforcement Decree Article 8 (Business Registration Number) · Legal basis for 10-digit Korean business number assignment rules, checksum, and type codes (corporate/sole-proprietor/tax-exempt)
NTS Hometax — Business Status Inquiry · Official channel for verifying active business status, suspension/closure, and tax classification
National Tax Service (NTS) — Business Registration · Business registration application·amendment·closure + call center (☎ 126)

This tool validates format (checksum + type code) entirely in your browser. Actual business status, dealer info, and representative verification must be confirmed via Hometax Business Status Inquiry or NTS (☎ 126). Always verify before issuing tax invoices, signing contracts, or qualifying expenses.

FAQ

What is a Korean Business Registration Number (BRN)?

A 10-digit number issued by Korea's National Tax Service when a person or entity registers a business. Format: XXX-XX-XXXXX. Required for tax filings, invoices, and B2B transactions in Korea.

How is the BRN checksum calculated?

Multiply the first 9 digits by weights [1,3,7,1,3,7,1,3,5], then add floor(digit[8] × 5 / 10) as a special correction. Take (10 − sum mod 10) mod 10 — this must equal the 10th digit. Standard NTS algorithm.

Why does my BRN show 'foreign' or 'tax-exempt' type?

The 4th–5th digits classify the business: 84 = foreign corporation (Korean branch/liaison of an overseas entity), 90–99 = tax-exempt individual (e.g., farming, fishing, certain professional services). Foreign residents who register a Korean sole proprietorship typically receive 01–79 (taxable) or 90–99 (tax-exempt).

Does this tool confirm my business is actually active?

No. This tool only validates format (checksum + type code). For active/suspended/closed status, dealer info, or representative name, use Hometax (Korea's official tax portal at hometax.go.kr) or call NTS at 126.

What's the difference between a BRN and a Corporate Registration Number?

BRN (사업자등록번호) is 10 digits, issued by the tax office, used for tax filings and invoices. Corporate Registration Number (법인등록번호) is 13 digits, issued by district court registries when a corporation is incorporated, used for legal contracts and registry. They are separate numbers — one entity has both. This tool validates only the 10-digit BRN; for the 13-digit Corporate Registration Number, use the Corp Reg Number Validator.