American entrepreneurs in Korea face a unique tax situation: the US taxes its citizens on worldwide income regardless of where they live, while Korea taxes all income earned within its borders. Understanding how the Korea-US tax treaty interacts with your obligations in both countries is essential for avoiding double taxation and staying compliant.
The Korea-US Tax Treaty at a Glance
The current Korea-US income tax treaty has been in force since 1979 and provides several key protections for US citizens doing business in Korea:
- Dividends: Withholding tax reduced from 20% to 15% (or 10% if the US shareholder owns at least 10% of the Korean company's voting stock)
- Interest: Withholding tax reduced from 22% to 12%
- Royalties: Withholding tax reduced from 22% to 15%
- Business profits: Only taxable in Korea if you have a "permanent establishment" (PE) there — meaning a fixed place of business, branch, or dependent agent
Foreign Tax Credit (FTC) — Your Main Tool Against Double Taxation
The most important mechanism for US citizens is the Foreign Tax Credit. Taxes paid to Korea on income that is also subject to US tax can be credited against your US tax liability — dollar for dollar, up to the US tax rate on that income. In most cases, because Korea's corporate tax rates are comparable to or higher than US rates, the FTC eliminates most or all additional US tax owed on Korean-sourced income.
Important: The FTC applies to taxes paid — not taxes deferred. If you are delaying tax payments in Korea, you may not be able to claim the credit on your US return for the same period. Timing matters.
GILTI — Global Intangible Low-Taxed Income
US shareholders who own 10% or more of a Controlled Foreign Corporation (CFC) — which includes most Korean subsidiaries wholly owned by Americans — must report Global Intangible Low-Taxed Income (GILTI) on their US returns. GILTI captures income in foreign companies that isn't sufficiently taxed overseas.
Korea's corporate tax rates (9–24%) are generally above the GILTI minimum rate of 10.5%, so most US shareholders in Korean companies will not owe additional GILTI tax. However, the calculation is complex and depends on your company's income composition, deductions, and the FTC application. This is an area where US and Korean tax professionals must work together.
FBAR and FATCA Reporting
US citizens with Korean corporate or personal bank accounts must comply with:
- FBAR (FinCEN 114): Filed annually if the aggregate balance of all foreign accounts exceeds USD 10,000 at any point during the year
- FATCA (Form 8938): Filed with your US tax return if foreign financial assets exceed USD 200,000 (USD 400,000 for joint filers) at year end
Failure to file these forms carries severe penalties — up to USD 10,000 per violation for FBAR, and potentially more for wilful non-compliance.
What About Self-Employment Tax?
If you are the sole shareholder and director of a Korean company and pay yourself a salary, the Korea-US totalization agreement means you should be contributing to either the Korean National Pension or US Social Security — not both. Korea and the US have a social security totalization agreement that prevents dual contributions and allows periods of coverage to be combined for benefit eligibility purposes.
US tax compliance for Korea-based business owners is genuinely complex. We collaborate with US-qualified CPAs to provide coordinated Korean accounting and US filing guidance. Get in touch to discuss your situation.