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Validate South Korea Tax ID Numbers via API
When building B2B applications that serve South Korea (대한민국 (Daehan Minguk)), validating your customers' 사업자등록번호 (Saeopja Deungrok Beonho — Business Registration Number) is essential for B2B compliance and protecting your business from tax liability.
The TaxID API provides instant format validation and live lookup for South Korea 사업자등록번호 numbers via NTS (National Tax Service / 국세청). Every request returns the validation status with sub-100ms response times for cached results.South Korea applies a standard rate of 10% (사업자등록번호).
QUICK START
curl -H "Authorization: Bearer YOUR_API_KEY" \ http://localhost:3000/api/v1/validate/KR/123-45-67890
Code examples
Choose your language. Every example validates a South Korea VAT number and returns the registration status with company details.
const res = await fetch('http://localhost:3000/api/v1/validate/KR/123-45-67890', {
headers: { 'Authorization': 'Bearer YOUR_API_KEY' }
});
const data = await res.json();
// { valid: true, status: "active", company_name: "...", country_code: "KR", cached: false }
console.log(data);When to validate South Korea tax ID numbers
B2B invoicing and accounts payable
When issuing or receiving invoices from South Korea businesses, validating the 사업자등록번호 (Saeopja Deungrok Beonho — Business Registration Number) ensures the identifier is genuine before committing the transaction to your ERP. Invalid or fabricated tax IDs are a leading vector for invoice fraud and can result in rejected filings or audit penalties.
SaaS and e-commerce checkout
If your platform serves South Korea business customers, collecting and validating their 사업자등록번호 (Saeopja Deungrok Beonho — Business Registration Number) at checkout is required for accurate tax treatment, correct invoicing, and downstream reporting. An invalid tax ID at the point of sale creates a correction burden across your finance stack.
Supplier and marketplace onboarding
For procurement platforms and regulated marketplaces onboarding South Korea sellers or vendors, validating the 사업자등록번호 (Saeopja Deungrok Beonho — Business Registration Number) at registration prevents fraudulent or duplicate accounts from entering your ecosystem. Validate once at onboarding, then re-validate periodically to detect deregistrations or changes.
About South Korea VAT format (사업자등록번호)
South Korea applies a flat 10% VAT (부가가치세) with no reduced rates. The 10-digit Business Registration Number is formatted as XXX-XX-XXXXX. Korea is a major technology market; companies like Samsung, LG, Kakao, and Naver require VAT validation for B2B transactions.
| Field | Value |
|---|---|
| Country code | KR |
| Local name | 사업자등록번호 (Saeopja Deungrok Beonho — Business Registration Number) |
| Format | 3 digits + - + 2 digits + - + 5 digits |
| Regex pattern | ^[0-9]{3}-[0-9]{2}-[0-9]{5}$ |
| Example | 123-45-67890 |
| VIES supported | No |
VAT rates in South Korea
South Korea applies a standard 사업자등록번호 rate of 10%. Reduced rates of 0% apply to essential goods and services.
| Rate type | Percentage | Currency |
|---|---|---|
| Standard rate | 10% | KRW |
| Reduced rate | 0% | KRW |
Frequently asked questions
What is the South Korea tax ID number format?
South Korea tax ID numbers (사업자등록번호 (Saeopja Deungrok Beonho — Business Registration Number)) follow the format: 3 digits + - + 2 digits + - + 5 digits. A valid example is 123-45-67890. The TaxID API validates the format locally and where possible checks against the NTS (National Tax Service / 국세청), ensuring you only accept properly registered businesses.
Should I validate 사업자등록번호 numbers when transacting with South Korea businesses?
Validating 사업자등록번호 numbers reduces fraud risk, prevents invalid identifiers from entering your accounting system, and is required by many B2B contracts and procurement platforms. While mandatory rules vary by jurisdiction, validating at onboarding is widely considered best practice — especially for SaaS, marketplace, and fintech platforms with global customer bases.
What is the standard tax rate in South Korea?
The standard tax rate in South Korea is 10% (사업자등록번호). Reduced rates of 0% apply to certain goods and services such as food, books, and medical supplies. The TaxID API's /rates endpoint returns all current rates for programmatic access.
How long does South Korea tax ID validation take with TaxID?
For cached results (previously validated in the last 24 hours), the TaxID API responds in under 10ms. Format validation is instantaneous. For uncached requests requiring a live lookup against NTS (National Tax Service / 국세청), response time is typically 100–500ms. Valid numbers are cached for 24 hours; invalid numbers are cached for 1 hour.
How does the TaxID API validate South Korea 사업자등록번호 numbers?
The TaxID API validates South Korea 사업자등록번호 numbers in two steps: first it checks the format against the official pattern (3 digits + - + 2 digits + - + 5 digits), then it queries NTS (National Tax Service / 국세청) where a live API is available. South Korea applies a flat 10% VAT (부가가치세) with no reduced rates. The 10-digit Business Registration Number is formatted as XXX-XX-XXXXX. Korea is a major technology market; companies like Samsung, LG, Kakao, and Naver require VAT validation for B2B transactions.
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