The tax on a yen gain depends on the wrapper. FX deposit currency gains are untaxed, but a Korea-listed yen ETF's trading profit is dividend income withheld at 15.4% and counted toward the aggregate financial income threshold.
US dividends lose 15% at source and nothing more in Korea — lighter than the 15.4% on Korean dividends. The real split comes at 20 million won of annual financial income.
From January 1, 2026, cash dividends from Korean listed firms with a payout ratio of 40% or more can be taxed separately at 14–30% instead of being rolled into comprehensive income. The break-even sits near a 50 million won taxable base.
Only financial income above 20 million won gets rolled into comprehensive taxation, but health insurance starts counting at 10 million won. A 1-million-won difference can create 480,000 won a year in premiums.
Dividends from US stocks are withheld once at 15% with nothing added in Korea. Chinese dividends face an extra 4.4% at home. Here is the full arithmetic on 10 million won of dividends — and what changes above the 20 million won threshold.
Two ETFs tracking the same S&P 500 index are taxed differently in Korea. At 8.33 million won of annual realized gain, the 15.4% dividend route and the 22% capital gains route cost exactly the same. Here is where each one wins.