Summary
If you make 104,000,016 원 a year living in South Korea, you will be taxed 23,575,726 원. That means that your net pay will be 80,424,290 원 per year, or 6,702,024 원 per month. Your average tax rate is 22.7% and your marginal tax rate is 29.0%. This marginal tax rate means that your immediate additional income will be taxed at this rate. For instance, an increase of 100 원 in your salary will be taxed 29 원, hence, your net pay will only increase by 71 원.
Bonus Example
A 1,000 원 bonus will generate an extra 710 원 of net incomes. A 5,000 원 bonus will generate an extra 3,550 원 of net incomes.