Social Security tells payees to spend a child’s SSI on the child’s “current maintenance,” which includes things like food, shelter, clothing, medical care, and personal care items. First, you should use the money to make sure your child has food and shelter.our child’s SSI payment amount will vary depending on the state you live in and whether your child has any countable income, but the federal base rate for 2015 is $733/month. (Read Nolo's article on how much SSI pays for more information.).