Summary
If you make 40,170,000 OMR a year living in Oman, you will be taxed 3,213,600 OMR. That means that your net pay will be 36,956,400 OMR per year, or 3,079,700 OMR per month. Your average tax rate is 8.0% and your marginal tax rate is 8.0%. This marginal tax rate means that your immediate additional income will be taxed at this rate. For instance, an increase of 100 OMR in your salary will be taxed 8 OMR, hence, your net pay will only increase by 92 OMR.
Bonus Example
A 1,000 OMR bonus will generate an extra 920 OMR of net incomes. A 5,000 OMR bonus will generate an extra 4,600 OMR of net incomes.