Summary
If you make 243,000,000 원 a year living in South Korea, you will be taxed 81,342,295 원. That means that your net pay will be 161,657,705 원 per year, or 13,471,475 원 per month. Your average tax rate is 33.5% 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.