Until December 18, 2026, the rule is the same as it's been for decades: every male U.S. citizen between the ages of 18 and 25 has to register with the Selective Service System within 30 days of turning 18. Certain non-citizen men in the same age range living in the U.S. — including most permanent residents — have to register too. * The formal criminal penalty for skipping registration is severe on paper: a felony charge carrying up to a $250,000 fine and up to 5 years in prison. In practice, nobody has actually been prosecuted for failing to register since the 1980s — but the practical consequences that do get enforced are still real and immediate. * Not registering blocks access to federal jobs and federal student aid, including Pell Grants and federal student loans. Many states also tie a driver's license or state financial aid to Selective Service registration, meaning the requirement shows up in places that have nothing to do with the military. * The system itself is about to change in a way that removes the burden of remembering to register at all. Starting December 18, 2026, the requirement shifts from self-registration to automatic registration — the Selective Service System will register eligible men itself, using data pulled from other federal government databases, rather than requiring each person to submit their own registration. * Until that date arrives, the registration requirement still works the old way, and anyone who's turned 18 and hasn't registered yet should do so at sss.gov rather than assuming the automatic system already covers them.