Summary
If you make 381,332,640 원 a year living in South Korea, you will be taxed 142,766,738 원. That means that your net pay will be 238,565,902 원 per year, or 19,880,492 원 per month. Your average tax rate is 37.4% and your marginal tax rate is 45.8%. 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 45.82 원, hence, your net pay will only increase by 54.18 원.
Bonus Example
A 1,000 원 bonus will generate an extra 542 원 of net incomes. A 5,000 원 bonus will generate an extra 2,709 원 of net incomes.