Prepare my return taking my son & daughter as exemptions. I file Head of Household. She graduates during the year. So I decide to see what effect it would have on my return if I did not claim her as an exemption, but let her claim herself on her own return. I remove her as an exemption on my return and my taxable income decreases by $3,950, as it should. But I still owe the same tax. The amount of tax I owe did not change. Why is that?