Do you have to file an income tax?

To determine if you have to file a federal income tax return see Tables 1, 2, and 3 on pages 2, 3, and 4 of Publication 501:

http://www.irs.gov/pub/irs-pdf/p501.pdf

To determine if you have to file a state tax return, see the instructions that come with your state tax forms or the web site of your state tax agency.

Even if you are not required to file you probably want to file if you had any taxes withheld from your paycheck or from some other payment. The reason is that the amount withheld is never exactly the correct amount. If you are not required to file and you had taxes withheld, then you are almost certainly owed a refund. If you don't file you will forfeit your refund.