I will have a gross pay of $30,080 and $3,900 in federal taxes withheld this year. When I filled out my W-4 form I put Zero exemptions to cover myself so I do not have to owe anything. I am single and no children. Why does the Withholding Calculator say I will underpay by around $2,300? That does not seem right. Help please! I don't think should owe anything.