If your girlfriend lives with you while she looks for work and you support her financially, you may be able to claim her as a dependent when tax season rolls around. There are four tests that the IRS uses to determine whether your girlfriend qualifies as a dependent: the gross income test, total support, and member of household or relationship test.
Gross Income Test
If you intend to claim your girlfriend, she'll have to meet the IRS' definition of a "qualifying relative" since she doesn't make the cut as a qualifying child. Your girlfriend has to meet the gross income test, which changes from year to year. In 2011, if your girlfriend earned less than $3,700, she satisfied the gross income test.
Total support means you provided more than half your girlfriend's financial support for more than half the year. Paying for groceries, clothes, transportation and other living expenses are considered support. You wouldn't be able to claim support if you paid less than half her support and another person can claim your girlfriend as a dependent (such as her parents).
Member of Household
The IRS allows you to claim a "qualifying relative" such as your aunt, brother or grandparent even if they didn't live with you for the entire year. However, your girlfriend is a different story. She must live with you as a member of your household for the entire year.
Even though you're in a relationship, the IRS definition of relationship means a spouse, child, sibling, descendant or an in-law. But you can still meet the relationship test if you cohabit — so long as it doesn't violate the law. For example, you can't still be married to someone else. Also, check your state law, because some states don't allow you to claim your girlfriend as a dependent if you two aren't married or recognized as being in a common-law marriage.