Question: how long do you have to sign up for the draft after you turn 18?
Answer: Who Must Register with Selective Service. Almost all men age 18-25 who are U.S. citizens or are immigrants living in the U.S. are required to be registered with Selective Service. U.S. law calls for citizens to register within 30 days of turning 18 and immigrants to register within 30 days of arriving in the U.S.