Qualifying Dependents

• To qualify as a dependent for the purposes of filing your federal income tax return, the person you intend to claim must three specific tests: The dependent taxpayer test, the joint return test, and citizen or residential status. The first test means that you cannot claim a dependent if you yourself or your spouse can also be claimed as a dependent on another person's tax return. The joint return test means you cannot claim someone who files a joint return unless that joint return is a claim for a refund with no tax liability. Lastly, the dependent must be a citizen or legal resident of the U.S., Canada or Mexico.
  
  

Tests for a Qualifying Child

• Children must be a child your own child, stepchild, foster child, brother or sister, stepbrother or stepsister, or a descendant of any of them. Half siblings can also qualify. Descendants of any of these people also qualify as well. You can claim them up through the age of 18. You may also claim them up to age 24 if they are enrolled as a full-time student. The child must have lived with you for at least half of the tax year in question. Finally, only one taxpayer may claim a qualifying child. There must, however, be a blood or legal formal relationship between you and the child. Assignment as a custodial foster parent or adoptive parent works for the purposes of determining the child's eligibility as a dependent.
  
  

Tests for a Qualifying Relative

• You may claim a nonchild relative if that individual lives with you for for the entire year as a member of your household, your relationship does not violate the law, and he or she earns less than $3,650 per year. Some relatives, however, do not have to live with you. However, you must provide at least half of that individual's support for the tax year in question. The individual cannot be a qualifying child of another person.
  
  

In-Laws

• If you are married and the sole income earner or primary breadwinner, you may claim a spouse's relative on your tax return, even though that relative is not related to you except by marriage.
  
  

Nonrelatives

• Provided the individual meets all the tests for a qualifying relative, you can claim a nonspousal partner as a dependent unless local or state law renders your relationship illegal. For example, some states still technically prohibit cohabitation. These states are West Virginia, Virginia, North Dakota, North Carolina, Michigan, Mississippi and Florida. Some local governments restrict the practice as well.