What are the Rules for Claiming Children on Taxes?

Claiming a child as a dependent on your taxes means you'll qualify for more deductions, and possibly tax credits as well. The IRS requires taxpayers to pass a set of four tests in order to claim a child. You also must have a valid form of identification for the child, like a Social Security number, in order to satisfy the IRS.

To claim a child as a dependent, your relationship with the child must fall into one of the IRS-recognized categories. You potentially can claim your children by blood or adoption or foster children as dependents. If you have a sibling or step-sibling that you support -- for example, a younger sister -- she also may qualify as a dependent child. You also may claim subsequent generations of family members if they otherwise would meet IRS requirements. For example, your granddaughter or niece potentially could be your dependents.

Any dependent child must have resided with you for more than half the year, excluding any temporary absences. This doesn't apply to newborn children born during the tax year or children who died during the tax year. For example, if you had a baby on Dec. 1, 2015, you can claim her as a dependent for the 2015 tax year.

The child must be under 19 for you to claim her in most cases. However, you can claim dependents between 19 and 24 as long as they are attending school at least five months out of the year. If the child is permanently disabled, you can claim him at any age.

The child can't have provided more than half of his own financial support during the tax year. The child, can, however, receive support from other people. For example, if you provided one third of the financial support for your child, your ex-husband provided another third and the child provided a third for herself, you may be able to claim her as a dependent.

To claim someone as a dependent, she must be a U.S. citizen, a national or a resident of U.S., Canada or Mexico. The only exception to this rule is for adopted children. You can claim a child as a dependent even if she's married. However, you can't claim her if she files a joint tax return, unless the return is only filed to claim a refund.

You'll need to know the dependent's Social Security number and full legal name to claim the child as a dependent. You can apply for a Social Security number for the child at the hospital when she's born or by completing Form SS-5.

Some adopted children aren't eligible for a Social Security number immediately, so the IRS allows you to claim them if they have an individual taxpayer identification number. You can request an ITIN for a child here.