HelloCustomer Thank you for coming to Just Answer and allowing us to help you with your tax questions. If a child is or will be 19 years old by the end of December 2009 and is not a full-time student, then she will not be a qualified child for tax purposes. If a child is 19 years old and a full-time student, and she doesn't provide over half of her total support (I'll define total support lower down), then the daughter is a qualified child of her father and can be claimed for all tax benefits. If a child is over age 19 and provides over half of her own support, then she is not a dependent of her parent for tax purposes. If the daughter isn't a qualified child, then her father can't use her to claim head of household filing status or earned income credit. If the daughter doesn't provide over half of her own support, then the father can claim the daughter as a dependent for the dependent's personal exemption only, but he still can't use her to qualify him as head of household or to receive earned income credit.
If the daughter is 19 years old and provides over half of her own support, then she can't be a dependent on her father's return and if she earned over $8950 in 2009, then she is required to file a tax return and she will claim her own personal exemption. If she earned less than $8950, she will not be required to file a return, but she will be able to recover any income tax withheld from her paychecks if she does file. As long as she is over 19 and provides over half of her own support, she will claim her own personal exemption.
In order to determine who provides support for the daughter, you need to add up all money spent on behalf of the daughter, separate the money based on who provided it, and determine who provided over 50% of the daughters support. In this calculation, add in the amount of rent that would be charged by a stranger for similar living accomodations in your area (look at the rent costs in want ads for apartments in your area) and subtract the amount of rent she actually pays to her father. All of the money used to support the daughter should come from the father, the daughter, and, if applicable, any government benefits. Figure out housing costs (minus rent paid), food costs, utility costs, clothing costs, medical and dental costs, and any other money used to support the daughter. Then use these costs and figure out how much is paid by the father, by the daughter, and by other sources (usually the government). If the amount paid by the father is 50% of the total costs, the father can claim the daughter as a dependent and use the daughter's personal exemption. If the daughter pays over 50% of the total costs, she is not a dependent of her father and she can file her own return and use her own personal exemption. The daughter will file as single.
Sorry that this is so complicated. It's a complicated part of the tax code. I will be happy to provide further information or clarify anything that doesn't make sense to you.