SSI & Age 18 Redetermination People Living with Disabilities Download Document Tags: At-a-Glance, SSI and SSDI Appeals and Denials, Supplemental Security Income Language: English As the criteria for SSI is different for children and adults, once a child reaches the age of 18, a review is scheduled to determine whether their condition or illness meets the SSI definition of disability for an adult. This document discusses what to expect during this review.