A child up to 18 years old may receive Supplemental Security Income child benefits if they are found
         disabled by Social Security and the parents income and resources are low enough.  Social Security defines disability
         in children.  Under title XVI, a child under age 18 will be considered disabled if he or she has a 
medically determinable physical or mental impairment or combination of impairments that causes marked and severe functional limitations, and that can be expected to cause death
         or that has lasted or can be expected to last for a continuous period of not less than 12 months.
There
         is a three step process Social Security uses to determine if a child is disabled for child's SSI.
- First, 
         is the child working at substantial gainful activity (SGA) level.  If the child is working the claim for child's SSI will be denied.  If the child is not working we move to
         step 2.  
 - Step 2,  Does the child claimant have a severe impairment.  If not the child will be denied.  If the child has a severe impairment we move to step 3.  
 - Step
         3, does the child impairment meet, medically equal or functionally equal one of the listed impairments.
 
Most child SSI cases are decided ultimately on whether the child functionally equals one of the listed impairments. 
         If a child clearly meets a listing the child will usually win fairly quickly if all supporting medical records are in. 
         I am going to address the cases were a child does not meet any of the listing of impairments.
For a child
         to functionally equal a listed impairment the must have marked limitations in two domains or an extreme limitation in one. 
         The six domains are:
- Acquiring and Using Information
 - Attending and Completing Tasks
 - Interacting
         and Relating with Others
 - Moving About and Manipulating Objects
 - Caring for Yourself
 - Health and Physical
         Well Being
 
In each of these domains the child is compared to other children their age.  The Social Security
         Administration will look at each of these domains and determine if the child's limitations from her impairment in
         each domain is severe enough to be marked or extreme.  An impairment is considered marked if it seriously interferes
         with the child's overall abilities.  An impairment is generally considered marked if the child's functioning
         is at least 2 but no more than 3 standard deviations from the mean.  20 CFR $416.926a (e).  An impairment is considered
         extreme if it very seriously interferes with child's overall abilities.  An impairment is generally considered extreme
         if the child's functioning is at least 3 deviations below the mean.  If a child is found to have a marked limitations of
         2 domains or an extreme limitation of one then the impairment is functionally equivalent to a listed impairment. 
         20 CFR $416.926a.  So, if the child functionally equals a listed impairment they will be found disabled.
You
         may be unsure of how you go about applying for Child's SSI.  Make sure to bookmark this site so you can come back
         later.  If you want information on how to apply click on the link "how to apply for child's SSI" this will direct you to Social Security's web site. 
      
      
      So how does Social Security define a marked limitation in child SSI cases.  According to
         Program Operations Manual or POMS.We will find that you have a "marked" limitation
         in a domain when your impairment(s) interferes seriously with your ability to independently initiate, sustain, or complete
         activities. Your day-to-day functioning may be seriously limited when your impairment(s) limits only one activity or when
         the interactive and cumulative effects of your impairment(s) limit several activities. "Marked" limitation also
         means a limitation that is "more than moderate" but "less than extreme." It is the equivalent of the functioning
         we would expect to find on standardized testing with scores that are at least two, but less than three, standard deviations
         below the mean.
If you have not attained age 3, we will generally find that you have a "marked"
         limitation if you are functioning at a level that is more than one-half but not more than two-thirds of your chronological
         age when there are no standard scores from standardized tests in your case record.
If you are a child of any age
         (birth to the attainment of age 18), we will find that you have a "marked" limitation when you have a valid score
         that is two standard deviations or more below the mean, but less than three standard deviations, on a comprehensive standardized
         test designed to measure ability or functioning in that domain, and your day-to-day functioning in domain-related activities
         is consistent with that score.
For the sixth domain of functioning, "Health and physical well-being,"
         we may also consider you to have a "marked" limitation if you are frequently ill because of your impairment(s) or
         have frequent exacerbations of your impairment(s) that result in significant, documented symptoms or signs. For purposes of
         this domain, "frequent" means that you have episodes of illness or exacerbations that occur on an average of 3 times
         a year, or once every 4 months, each lasting 2 weeks or more. We may also find that you have a "marked" limitation
         if you have episodes that occur more often than 3 times in a year or once every 4 months but do not last for 2 weeks, or occur
         less often than an average of 3 times a year or once every 4 months but last longer than 2 weeks, if the overall effect (based
         on the length of the episode(s) or its frequency) is equivalent in severity.
How does Social
         Security define an extreme limitation in child SSI cases.
We will find that you have an
         "extreme" limitation in a domain when your impairment(s) interferes very seriously with your ability to independently
         initiate, sustain, or complete activities. Your day-to-day functioning may be very seriously limited when your impairment(s)
         limits only one activity or when the interactive and cumulative effects of your impairment(s) limit several activities. "Extreme"
         limitation also means a limitation that is "more than marked." "Extreme" limitation is the rating we give
         to the worst limitations. However, "extreme limitation" does not necessarily mean a total lack or loss of ability
         to function. It is the equivalent of the functioning we would expect to find on standardized testing with scores that are
         at least three standard deviations below the mean.
If you have not attained age 3, we will generally find
         that you have an "extreme" limitation if you are functioning at a level that is one-half of your chronological age
         or less when there are no standard scores from standardized tests in your case record.
If you are a child of any
         age (birth to the attainment of age 18), we will find that you have an "extreme" limitation when you have a valid
         score that is three standard deviations or more below the mean on a comprehensive standardized test designed to measure ability
         or functioning in that domain, and your day-to-day functioning in domain-related activities is consistent with that score.
For the sixth domain of functioning, "Health and physical well-being," we may also consider you to have
         an "extreme" limitation if you are frequently ill because of your impairment(s) or have frequent exacerbations of
         your impairment(s) that result in significant, documented symptoms or signs substantially in excess of the requirements for
         showing a "marked" limitation in DI 25225.020B.4. However, if you have episodes of illness or exacerbations
         of your impairment(s) that we would rate as "extreme" under this definition, your impairment(s) should meet or medically
         equal the requirements of a listing in most cases.