For many immigrants, becoming a U.S. citizen is an important final step in a longer immigration journey. Naturalization — the legal process of becoming a U.S. citizen — involves more than filing Form N-400. Eligibility can involve residence, physical presence, good moral character, English and civics requirements, and other factors.
Extended travel, criminal history, tax issues, inaccurate prior filings, immigration violations, and questions about permanent-resident status can affect a citizenship (naturalization) application. These situations should be reviewed before filing.
Some lawful permanent residents may qualify under a three-year rule instead of the general five-year residence framework, but the additional requirements matter.