Your monthly income before taxes is also called your gross income, and can be calculated from your base salary. Your take-home or net pay will most likely have tax deductions from federal, state and local entities, and thus will be lower than your gross pay. Your gross pay, rather than your net or take home pay, is what you use to figure your annual tax payments to the Internal Revenue Service and your state. To get your true monthly income, start by figuring your annual pay.

Step 1

Multiply the number of hours you work each day by your hourly wage. If your hours vary, take an average of daily work hours. If you make $12.00 per hour, and work an average of seven hours per day, your daily pay is $84.00.

Step 2

Figure out the total number of work days you will work in a year. For a five-day work week, this would be 260 days. Even if you don't work all those days, count them as long as you get paid for them (such as sick or vacation days).

Step 3

Multiply your daily pay by the number of work days in a year. For 260 work days at $84.00 per day, your annual gross pay would be $21,840.

Step 4

Divide your annual gross pay by 12 to get your monthly pay. For an annual gross income of $21,840, the monthly income before taxes is $1,820.