If you make 6,000,000 QAR a year living in Qatar, you will be taxed 300,000 QAR. That means that your net pay will be 5,700,000 QAR per year, or 475,000 QAR per month. Your average tax rate is 5.0% and your marginal tax rate is 5.0%. This marginal tax rate means that your immediate additional income will be taxed at this rate. For instance, an increase of 100 QAR in your salary will be taxed 5 QAR, hence, your net pay will only increase by 95 QAR.
A 1,000 QAR bonus will generate an extra 950 QAR of net incomes. A 5,000 QAR bonus will generate an extra 4,750 QAR of net incomes.