Summary
If you make 80,462,712 원 a year living in South Korea, you will be taxed 16,803,506 원. That means that your net pay will be 63,659,206 원 per year, or 5,304,934 원 per month. Your average tax rate is 20.9% and your marginal tax rate is 28.6%. 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 28.64 원, hence, your net pay will only increase by 71.36 원.
Bonus Example
A 1,000 원 bonus will generate an extra 714 원 of net incomes. A 5,000 원 bonus will generate an extra 3,568 원 of net incomes.