Korea applies progressive national income tax rates from 6% to 45% to the taxable income base. A higher bracket does not tax all income at its top rate.
What the rates apply to
The rates apply to the taxable income base after applicable income deductions, not directly to gross salary. Local income tax and tax credits are separate steps.
Brackets and quick calculation
The referenced brackets are 6%, 15%, 24%, 35%, 38%, 40%, 42% and 45%. A common quick formula is calculated tax = taxable base × bracket rate − the bracket’s progressive deduction. The deduction makes this equivalent to applying each rate only to its slice.
Example
For a KRW 40 million taxable base, the referenced 15% bracket and KRW 1.26 million progressive deduction give KRW 4.74 million calculated national income tax before tax credits and other adjustments.
Common confusion
Moving into a higher bracket does not make the entire salary subject to that rate. Withholding each month is an advance payment; the final amount is determined through settlement or filing.