Do children need to apply?

It depends on their age and whether they are traveling with a parent or guardian with TSA PreCheck®.  Family members ages 12 and under traveling with an eligible parent or guardian with a TSA PreCheck® indicator on their boarding pass can join them in the TSA PreCheck® lanes without applying.  Children between the ages of 13 and 17 who will be traveling on the same reservation as an enrolled parent or guardian may also access the TSA PreCheck® lanes, provided the children have the  TSA PreCheck® indicator on their boarding pass.  Children 13 to 17 may be randomly excluded from receiving TSA PreCheck® on their boarding pass.  In these cases, they must go through standard security screening.  Children 17 and under who will be traveling alone or without a TSA PreCheck®-eligible parent or guardian must apply for TSA PreCheck® to have access to expedited screening.