Summary
If you make 861,120,000 원 a year living in South Korea, you will be taxed 368,921,320 원. That means that your net pay will be 492,198,680 원 per year, or 41,016,557 원 per month. Your average tax rate is 42.8% and your marginal tax rate is 47.9%. 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 47.87 원, hence, your net pay will only increase by 52.13 원.
Bonus Example
A 1,000 원 bonus will generate an extra 521 원 of net incomes. A 5,000 원 bonus will generate an extra 2,607 원 of net incomes.