Summary
If you make 178,880,000 원 a year living in South Korea, you will be taxed 53,307,708 원. That means that your net pay will be 125,572,292 원 per year, or 10,464,358 원 per month. Your average tax rate is 29.8% and your marginal tax rate is 41.5%. 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 41.53 원, hence, your net pay will only increase by 58.47 원.
Bonus Example
A 1,000 원 bonus will generate an extra 585 원 of net incomes. A 5,000 원 bonus will generate an extra 2,924 원 of net incomes.