How to Use the Regulated-Zone Capital Gains Tax Calculator
Korea maintains a list of officially designated "regulated zones" where owners of multiple properties pay a nationwide surcharge — 20 percentage points for a second home, 30 points for a third or more — on top of the standard progressive capital gains rate. The United States has no equivalent nationwide system: capital gains on home sales are taxed under the federal long-term capital gains brackets (0%, 15%, or 20% depending on income), plus a 3.8% Net Investment Income Tax (NIIT) for higher earners.
What comes closest to Korea's regulated-zone surcharge in the U.S. is a small number of individual cities that have adopted their own extra transfer taxes on high-value or investment property sales — sometimes nicknamed "mansion taxes." This calculator lets you apply an example 4% city-level surcharge on top of the federal LTCG rate and NIIT, so you can see the combined effect, while making clear this is a local add-on, not a national policy.
Because tax brackets, NIIT thresholds, and any local surcharges change and vary by jurisdiction, treat this calculator as an educational estimate. Consult a tax professional or check current IRS and local tax authority guidance before making decisions based on these numbers.
Frequently Asked Questions
No. Korea designates specific regulated zones where multi-property owners pay a nationwide surcharge on top of the base capital gains rate. The U.S. has no equivalent national designation — only a small number of individual cities impose their own extra transfer or sale taxes on high-value or investment properties.
The Net Investment Income Tax is a 3.8% federal surtax on investment income, including capital gains, for higher-income taxpayers above IRS thresholds. This calculator applies it automatically when you select the top 20% long-term capital gains bracket, as a simplified proxy for high income.
A handful of U.S. cities have adopted their own additional transfer taxes on high-value real estate sales (sometimes called 'mansion taxes'), but these are local, city-specific policies — not a nationwide regulated-zone system.