Net monthly income refers to the paycheck employees receive from their employers. Employers deduct taxes and Social Security contributions before creating checks for their employees.
Employees who work multiple jobs get multiple paychecks. In order to determine their net monthly income, they must add the net income from both checks together.
A person who is not an employee has a much harder time determining his net monthly income. When clients make payments to him, the deductions have yet to be processed. Instead of net monthly income, the checks received from his clients reflect gross income. After filing quarterly taxes, the person can then estimate his net monthly income by utilizing the financial documents submitted to the Internal Revenue Service.