The child tax credit is available to taxpayers who incur expenses while caring for children during the year. To claim this credit, you must meet certain qualifications. You can typically claim this credit without having legal guardianship of the child in question, as long as you meet all of the other requirements.
You can claim one child tax credit for each of your qualifying children. A qualifying child is a child that you claim as a dependent who (1) lived with you for more than half of the tax year; (2) didn't provide more than half of his own support; (3) was under age 17 at the end of the tax year; and (4) meets the relationship test -- more on that in a bit. Qualifying children must also be United States citizens, resident aliens or U.S. nationals.
A child passes the relationship test if he is your daughter, son, foster child, adopted child, stepchild, sibling, stepbrother or stepsister. A child may also pass the relationship test if he is the descendant of another individual who would pass the test. For example, a niece, nephew, grandchild or great-grandchild could pass the relationship test and be your qualifying child.
A child could easily meet all of the requirements of being a qualifying child even if you don't have legal guardianship. For example, a child might live with you for more than half the year even if you are not his legal guardian, and legal guardianship doesn't change the child's relationship to you. Even if you plan to claim a child who isn't related to you by blood or marriage, legal guardianship isn't an issue: for example, most stepparents and foster parents are not a child's legal guardians, but they can often qualify to claim the child tax credit.
For each qualifying child, you can claim a credit of up to $1,000 on Form 1040. You must list the name and Social Security number of each qualifying child. Just as legal guardianship isn't a requirement for claiming the child tax credit, it doesn't automatically qualify you for the credit either. If you have legal guardianship of a child who doesn't live with you, for example, the child doesn't meet the residency requirement and you cannot claim the child tax credit.