Male students must register for the Selective Service within 30 days of their 18th birthday. All males, even from another country and not a U.S. citizen or if living undocumented in the U. S. must register. If a male is in a hospital, prison, or other institution when he turns 18, he has 30 days to register after being released. To register go to http://www.sss.gov.
Registering with the Selective Service does not mean joining the military. Not registering is against the law. Selective Service keeps a list of people who might be called on to serve our country in a national emergency. If the male is a senior and applies for the FAFSA, they can check a box on the FAFSA, and it will automatically register them.