Social Security child disability benefit is a type of Supplemental Security Income (SSI) program that provides financial support to children under the age of 18 who are disabled. Social Security uses different rules for determining disability in a child’s claim. For a child to be eligible for child disability, the parent’s household income must not exceed a certain level. To be found disabled, the child must have a physical or mental condition that causes marked and severe functional limitations. Under current regulations, a child must prove that he/she meets a listing or medically equals or functionally equals a listing. To functionally equal a listing, a child claimant must have marked limitations in two domains or extreme limitations in one domain. Domains are broad areas of functioning. Under the regulations, a marked limitation is one that interferes with child’s ability to independently initiate, sustain, or complete activities. Children on Supplemental Security Income (SSI) who reach age 18 are subject to a re-determination of disability under the adult standards. Children’s impairments must be established through medically acceptable evidence, which should include objective clinical findings. Since children, unlike adults, are unable to perform any type of work activity, Social Security has different methods to determine what residual functions he or she has. A child’s performance of school work and activities is often used to evaluate what a child is able to do and if that child is able to function at an age-appropriate level.