Green card holders who have been married to a U.S. citizen are entitled to apply for U.S. citizenship earlier. This is a very significant benefit because normally immigrants can only apply for citizenship after 5 years of lawful permanent residence. Many green card holders who enjoy this benefit obtained their green card on the basis of marriage to a U.S. citizen. By getting informed about how to best prepare an application for citizenship through marriage, you can increase your chances of being approved and eventually naturalized.