Korea Corp Registration Number Validator Supreme Court standard checksum

Korea has two corporate IDs — 10-digit BRN (tax) and 13-digit Corporate Registration Number (legal). This tool validates the latter: checksum, type, registry.

Corporate Registration Number ≠ BRN — they are different

BRN — Business Registration Number

XXX-XX-XXXXX (10 digits)

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

→ Use BRN Validator

Corporate Registration Number (법인등록번호)

XXXXXX-XXXXXXX (13 digits)

Issued by district court registries when a corporation is incorporated. For legal identity, contracts, DART disclosure. Validated by this tool.

Corporate Registration Number (13 digits)

0 / 13 digits Enter a Corporate Registration Number

Awaiting input

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Show how the checksum is calculated — vs BRN algorithm

13-digit anatomy:

Office (1-4)

XXXX

Type (5-6)

Sequence (7-12)

XXXXXX

Check (13)

Multiply the first 12 digits by weights [1,2,1,2,1,2,1,2,1,2,1,2], then check that (10 − sum mod 10) mod 10 equals the 13th digit. (Legacy format only — pre-2025-01-31.)

Position Digit × Weight = Product

BRN vs Corporate Registration Number — algorithm differences:

Item	BRN (10 digits)	Corp Reg # (13 digits)
Weights	[1,3,7,1,3,7,1,3,5]	[1,2,1,2,1,2,1,2,1,2,1,2]
9th-digit correction	Yes (floor(d[8]×5/10))	None
Modulo	10	10
Issuer	National Tax Service	District Court Registry
2025 change	Unchanged	Checksum eliminated 2025-01-31

※ Validated 100% client-side — no server transmission. Corporate Registration Numbers are public information; sharing the URL leaves the number in browser history.

Corporate type code reference (digits 5–6)

11 — Stock Company / Inc. (주식회사)
12 — Limited Company / Ltd. (유한회사)
13 — Limited Liability Company / LLC (유한책임회사)
14 — Limited Partnership (합자회사)
15 — General Partnership (합명회사)
21 — Incorporated Association / 22 — Foundation
31–51 — Special Corporation (school, social welfare, religious, medical, labor union, etc.)
71 — Non-corporate Association / Foundation
81–86 — Foreign Corporation (HQ / branch / other) — for foreign entities with Korean presence

※ Based on Supreme Court Rule on Corporate Registry Number Assignment, Annex 2 (2026-05).

Foreign corporations in Korea (codes 81–86)

If you represent a foreign entity that has incorporated a branch, liaison office, or HQ in Korea, your Corporate Registration Number will start with one of these codes in digits 5–6:

81 — Foreign Corporation HQ (overseas headquarters registered in Korea)
82 — Foreign Corporation Branch (Korean branch of overseas entity)
83–86 — Foreign Corporation (other registration types)

Foreign corporations registered in Korea also receive a separate Business Registration Number (BRN) with code 84 in the middle two digits (issued by the National Tax Service for tax purposes). The two numbers serve distinct purposes and are not interchangeable.

Registry office code reference (digits 1–4, major cities)

1101 — Seoul Central District Court Registry
1201 — Seoul Eastern District Court Registry
1301 — Seoul Western District Court Registry
1401 — Seoul Southern District Court Registry
1501 — Seoul Northern District Court Registry
1841 — Busan District Court Registry
2001 — Incheon District Court Registry
2401 — Daegu District Court Registry
2901 — Gwangju District Court Registry
3001 — Daejeon District Court Registry

Major cities only. Unmapped codes display as "registry undefined" — cross-check with Supreme Court Registry Information Plaza, Annex 1.

2025-01-31 format change

Per the Supreme Court Rule revision (2024-11-29), Corporate Registration Numbers issued from January 31, 2025 onward have:

Sequence number expanded from 6 digits → 7 digits
Checksum (error-detection) digit eliminated — all 13 digits now serve as sequence numbers
Sequence numbers that would collide with legacy issued numbers are skipped

When the checksum check fails, this tool displays a "new format possible" notice. To verify actual incorporation status, request a corporate registry certificate at iros.go.kr (Korea Supreme Court Internet Registry). The new electronic registry system (미래등기시스템) eliminated the checksum, making format-only validation unable to confirm post-2025 numbers.

How the checksum works (legacy format, pre-2025-01-31)

Strip non-digits to get d[0..12].
With weights W = [1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2], compute S = Σ d[i] × W[i] for i=0..11.
Expected check digit check = (10 − S mod 10) mod 10.
If check === d[12], the number is format-valid (legacy format).
If check !== d[12], the number may be post-2025 (new format) — confirm via iros.go.kr.

Verified sources: Korean cryptography references (dukgun.com, susemeee gist), Namu Wiki entry on Corporate Registration Number, Korean Bar Association notice on the 2025 format change. Public test case: Samsung Electronics 130111-0006246 — products [1,6,0,2,1,2,0,0,0,12,2,8] / sum 34 / (10-4)%10=6 = d[12] ✓.

FAQ

What is a Korean Corporate Registration Number, and how is it different from a BRN?

The Corporate Registration Number (법인등록번호) is a 13-digit identifier issued by Korean district court registries when a corporation is incorporated. It is used for legal entity identification, court filings, contracts, and public disclosure (DART). The Business Registration Number (BRN, 사업자등록번호) is a 10-digit identifier issued by the National Tax Service for tax identification — invoices, tax filings, business banking. A single Korean corporation holds both numbers — they serve distinct purposes and are not convertible. This tool validates the 13-digit Corporate Registration Number only; for BRN, use the BRN Validator.

How does the 13-digit Corporate Registration Number break down?

Digits 1–4: Registry office code (e.g., 1101 = Seoul Central District Court). Digits 5–6: Corporate type code (e.g., 11 = Stock Company / Inc., 12 = Limited Company). Digits 7–12: Sequence number (registration number). Digit 13: Checksum (error-detection digit). Note: numbers issued from January 31, 2025 onward have eliminated the checksum — all 13 digits now serve as sequence numbers under the new electronic registry system.

How is the checksum calculated, and how does it differ from the BRN checksum?

Multiply the first 12 digits by weights [1,2,1,2,1,2,1,2,1,2,1,2], sum them, then (10 − sum mod 10) mod 10 must equal the 13th digit. This differs from the 10-digit BRN checksum, which uses irregular weights [1,3,7,1,3,7,1,3,5] plus a special 9th-digit correction (floor(d[8] × 5 / 10)). The two algorithms are not interchangeable — using BRN logic on a Corporate Registration Number will give wrong results.

My number fails the checksum check — does that mean it is invalid?

Not necessarily. As of January 31, 2025, Korea's Supreme Court eliminated the checksum digit when launching the new electronic registry system (미래등기시스템). Numbers issued after that date now use all 13 digits as the sequence number, so they may not pass the legacy checksum check. If your number is post-Jan 2025, the failure is expected. To confirm actual registration status, request a corporate registry certificate (등기부등본) at iros.go.kr.

Does this tool confirm that the corporation is actually registered or active?

No. This tool validates format only (length + checksum + type code + registry office code). For actual incorporation status, dissolution, executive officers, or registered capital, request a registry certificate at iros.go.kr (Korea Supreme Court Internet Registry) or, for listed companies, search DART (Korea's electronic disclosure system). Foreign corporations with a Korean branch can also request certified registry abstracts via the same channels.