evidence: Males who have lived in the United States (or received their green card) between the ages of 18 and 26 must register with the Selective Service System. Registration usually must be completed within 30 days after turning 18 but not after turning 26. [...] - Are over 26 years old - Did not live in the United States between the ages of 18 and 26 - Have lived in the United States between the ages of 18 and 26 but under a lawful status other than "green card holder" during that entire period - Were born after March 29, 1957 and before December 31, 1959 (Selective Service was inactive during the time that men born in these years would have turned 18) [...] If you have not turned 26 and did not already register with Selective Service, it’s important to register before applying for naturalization. Otherwise, your U.S. citizenship application will most likely be denied.