Summary
If you make 124,259,980 원 a year living in South Korea, you will be taxed 31,011,301 원. That means that your net pay will be 93,248,679 원 per year, or 7,770,723 원 per month. Your average tax rate is 25.0% and your marginal tax rate is 40.7%. 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 40.69 원, hence, your net pay will only increase by 59.31 원.
Bonus Example
A 1,000 원 bonus will generate an extra 593 원 of net incomes. A 5,000 원 bonus will generate an extra 2,966 원 of net incomes.