Summary
If you make 4,237,992 OMR a year living in Oman, you will be taxed 339,039 OMR. That means that your net pay will be 3,898,953 OMR per year, or 324,913 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.