Summary
If you make 1,989,997 บาท a year living in Thailand, you will be taxed 369,249 บาท. That means that your net pay will be 1,620,748 บาท per year, or 135,062 บาท per month. Your average tax rate is 18.6% and your marginal tax rate is 29.0%. This marginal tax rate means that your immediate additional income will be taxed at this rate. For instance, an increase of 100 บาท in your salary will be taxed 29.01 บาท, hence, your net pay will only increase by 70.99 บาท.
Bonus Example
A 1,000 บาท bonus will generate an extra 710 บาท of net incomes. A 5,000 บาท bonus will generate an extra 3,550 บาท of net incomes.