If you make $ 8,000,000 a year living in Taiwan, you will be taxed $ 2,382,515. That means that your net pay will be $ 5,617,485 per year, or $ 468,124 per month. Your average tax rate is 29.8% and your marginal tax rate is 40.0%. This marginal tax rate means that your immediate additional income will be taxed at this rate. For instance, an increase of $ 100 in your salary will be taxed $ 40, hence, your net pay will only increase by $ 60.
A $ 1,000 bonus will generate an extra $ 600 of net incomes. A $ 5,000 bonus will generate an extra $ 3,000 of net incomes.