Being able to claim someone as a dependent entitles you to claim an exemption for that person on your taxes. If your dependent receives Supplemental Security income checks each month, this alone may not disqualify you from claiming her as a dependent, but other additional rules apply.
As a Qualifying Child
A dependent must be either a "qualifying child" or a "qualifying relative." A qualifying child covers your children, including foster and stepchildren, half, full and step siblings, and any descendant of these individuals. The child must live with you for more than half the year.
There are no income limitations for qualifying children, so the fact that your dependent receives SSI checks because of a disability or blindness is irrelevant. There is a requirement, however, that the child not provide more than half of her own support. As long as her SSI checks aren’t used to pay more than half of her living expenses and the other dependent requirements are satisfied, SSI isn’t a barrier to claiming a qualifying child as a dependent.
As a Qualifying Relative
If the person can’t be a qualifying child – if she's your mother, for example – you might still be able to claim her as a qualifying relative. Some qualifying relatives must live with you all year, although this rule does not apply to parents. You must provide more than half her support for the year.
A qualifying relative’s total gross income has to be less than the exemption amount for the year, which is $4,050 in 2017. Gross income excludes tax-exempt income, such as SSI so it's possible that the amount and frequency of your dependent’s SSI payments can prevent you from claiming her on your taxes.