9 X 40 = 360. 20 X 13.50 = 270 equals 630 So take home should be around 440
You may be filing single, how many deductions are you claiming on your W4?
I would claim married, filing 4 exemptions. Although I am NOT a tax expert, you with 3 kids will probably not have to pay much (if anything) in taxes. If you filed single with NO exemptions you are having WAY too much withheld.