Summary
If you make 648,960,000 원 a year living in South Korea, you will be taxed 267,357,544 원. That means that your net pay will be 381,602,456 원 per year, or 31,800,205 원 per month. Your average tax rate is 41.2% 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.