If you make RM 1,800,000 a year living in Malaysia, you will be taxed RM 659,982. That means that your net pay will be RM 1,140,018 per year, or RM 95,002 per month. Your average tax rate is 36.7% and your marginal tax rate is 39.0%. This marginal tax rate means that your immediate additional income will be taxed at this rate. For instance, an increase of RM 100 in your salary will be taxed RM 39, hence, your net pay will only increase by RM 61.
A RM 1,000 bonus will generate an extra RM 610 of net incomes. A RM 5,000 bonus will generate an extra RM 3,050 of net incomes.