In order to claim an exemption for a child on your federal income tax return, the child does not necessarily have to be your own child. You may be able to claim an exemption for a child as a qualifying child or a qualifying relative.
One of the tests that must be met for a qualifying child is the relationship test. According to the IRS, to meet this test the child must be your son, daughter, stepchild, adopted child, foster child, or a descendant of any of them. For example, a grandchild would qualify.
Or the child must be your brother, sister, half brother, half sister, stepbrother, stepsister, or a descendant of any of them. For example, a niece or nephew would qualify. If you are living together but are not married, you could not claim an exemption for your partner’s child as your qualifying child, even if you provide more than half his or her support, because you do not meet the relationship test.
If the child meets the relationship test, then there are four other tests that must also be met in order to claim an exemption for a qualifying child: age, residency, support, and joint return. Also, the child must be a U.S. citizen, U.S. resident alien, U.S. national, or a resident of Canada or Mexico.
To meet the age test, the child must be under age 19 at the end of the year or must be a full-time student under age 24 and younger than you, or your spouse if you are married filing jointly. For example, if you are 21 and are supporting your brother who is a full-time student and is 23, your brother would meet the relationship test but not the age test, so you could not claim an exemption for him as a qualifying child. If you are married filing jointly, the child must be younger than you or your spouse, but not necessarily younger than both of you. A child who is permanently and totally disabled meets the age test regardless of his or her age.
The residency test requires that the child lived with you for more than half the year, except for temporary absences such as due to illness, education, business, vacation, or military service. If you are divorced or separated, normally the custodial parent would meet the residency test. IRS Publication 501 describes various different scenarios to determine who the custodial parent is for tax purposes based on the number of nights the child lives with each parent.
The noncustodial parent could qualify to claim the exemption if the custodial parent signs a written declaration that he or she will not claim the exemption. This could be part of the divorce or legal separation agreement.
To meet the support test for a qualifying child, the child must not have provided more than half of his or her own support for the year.
To meet the joint return test for a qualifying child, the child must not file a joint return, unless it is only as a claim for a refund. Filing a joint return to claim a credit, such as the earned income credit, would not qualify as an exception to this test.
If you do not meet the above tests to claim an exemption for a qualifying child, you may be able to claim an exemption for the person as a qualifying relative. This is provided that no one else could claim an exemption for the person as a qualifying child.
To be a qualifying relative, the person must be related to you or live in your home all year as a member of your household, except for temporary absences. And your relationship must not be in violation of local law. The person’s gross income for the year must be less than the exemption amount ($3,700 in 2011), and you must provide over half the person’s support.
Therefore, you could claim an exemption for someone you live with who is not related to you, for example if you are living together but not married. You could also claim an exemption for a child who lives with you. Your own child, or a child you have with your partner could be a qualifying child or a qualifying relative for you, and your partner’s child could be a qualifying relative for you if the tests are met.
The states that allow same sex marriages or domestic registered partners may have different rules for filing jointly and claiming exemptions for children. You should check the rules for filing status and the exemptions you can claim in the state where you file your state income tax return.
Publication 501, Exemptions, Standard Deduction, and Filing Information, IRS