Summary
If you make 15,123,333 원 a year living in South Korea, you will be taxed 1,819,708 원. That means that your net pay will be 13,303,625 원 per year, or 1,108,635 원 per month. Your average tax rate is 12.0% and your marginal tax rate is 13.0%. 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 12.99 원, hence, your net pay will only increase by 87.01 원.
Bonus Example
A 1,000 원 bonus will generate an extra 870 원 of net incomes. A 5,000 원 bonus will generate an extra 4,351 원 of net incomes.