Eligibility
To apply for naturalisation you must be at least 18 and hold a green card for five years (three years if married to a U.S. citizen). You need to show continuous residence in the United States during that period, including at least 30 months of physical presence. You must also have lived in the state or USCIS district where you apply for at least three months.
Applicants are expected to demonstrate good moral character, an attachment to the principles of the U.S. Constitution and a willingness to take the Oath of Allegiance. Serious criminal convictions or outstanding tax obligations may render you ineligible.