Summary
If you make 256,880,004 원 a year living in South Korea, you will be taxed 87,417,790 원. That means that your net pay will be 169,462,214 원 per year, or 14,121,851 원 per month. Your average tax rate is 34.0% and your marginal tax rate is 43.8%. 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 43.78 원, hence, your net pay will only increase by 56.22 원.
Bonus Example
A 1,000 원 bonus will generate an extra 562 원 of net incomes. A 5,000 원 bonus will generate an extra 2,811 원 of net incomes.