Wages or service fees paid in foreign currency are, in principle, converted to Korean won using the "basic exchange rate or arbitrated exchange rate under the Foreign Exchange Transactions Act" as of the date the income was received. If wages are paid regularly each month, the exchange rate on each payment date applies.
For income that accrues over a period (such as business income), the exchange rate on the date the income arose (e.g., completion of the service) may apply instead — the correct timing varies by income type, so it's safest to confirm with a tax professional in ambiguous cases.
What to check when converting currency
Currency gains/losses from later conversion don't factor in
The wage itself is finalized using the exchange rate on the payment date. Any gain or loss from later converting that money at a different rate is unrelated to wage income calculation and generally isn't separately taxable (unless it arises from a distinct financial product).
Frequently Asked Questions
Related Topics
How Year-end Settlement Works: The Wage Income Tax Calculation Flow
A step-by-step walk-through of how Korea calculates your final year-end tax, from gross pay down to the amount actually owed or refunded.
Class B Wage Earners — When Your Salary Comes From Abroad
What "Class B" wage income means when your paycheck comes directly from an overseas employer, and how to file through a Class B Taxpayer Association.