If you are not a US citizen by birth, you can apply for citizenship through naturalization. The term naturalization refers to the process of an immigrant becoming a citizen of the United States. The following are the basic requirements for becoming a naturalized citizen.

Age

You must be at least 18 years of age or older to fill the 'Application of Naturalization' (Form N-400). Children younger than 18 years use "Application for a Certificate of Citizenship" (Form N-600), and naturalize automatically when their parents become citizens. Adopted children who acquired citizenship from parent(s) use the "Application for a Certificate of Citizenship on Behalf of an Adopted Child" (Form N-643).

Residency

You have been a lawful permanent resident (green card holder) for at least 4 years and 9 months. Your time as a permanent resident begins from the date you were granted the permanent resident status (the date given on your green card).

You are married to a US citizen and have been a lawful permanent resident for 2 years and 9 months (and continue to be married to the same person).

Residence and Physical Presence

You are eligible to apply for naturalization if you:

  • Have resided continuously as a lawful permanent resident in the U.S. for at least 5 years prior to filing with no single absence from the United States of more than one year
  • Have been physically present in the United States for at least 30 months out of the previous five years (absences of more than six months but less than one year shall disrupt the applicant's continuity of residence unless the applicant can establish that he or she did not abandon his or her residence during such period). OR you have been physically present for 18 months out of the 3 years and have not left the US for more than 6 months on any trip.
  • Must have been residing in the state you are applying in for at least three months.

Good Moral Character

You must be able to demonstrate that you have been a person of 'good moral character', have paid your taxes, have no criminal record, have not been involved in any illegal acts.

An applicant is permanently barred from naturalization if he or she has ever been convicted of murder. An applicant is also permanently barred from naturalization if he or she has been convicted of an aggravated felony as defined in section 101(a)(43) of the Act on or after November 29, 1990.

A person also cannot be found to be a person of good moral character if during the last five years he or she:

  • Has committed and been convicted of one or more crimes involving moral turpitude
  • Has committed and been convicted of 2 or more offenses for which the total sentence imposed was 5 years or more
  • Has committed and been convicted of any controlled substance law, except for a single offense of simple possession of 30 grams or less of marijuana
  • Has been confined to a penal institution during the statutory period, as a result of a conviction, for an aggregate period of 180 days or more
  • Has committed and been convicted of two or more gambling offenses
  • Is or has earned his or her principal income from illegal gambling
  • Is or has been involved in prostitution or commercialized vice
  • Is or has been involved in smuggling illegal aliens into the United States
  • Is or has been a habitual drunkard
  • Is practicing or has practiced polygamy
  • Has willfully failed or refused to support dependents
  • Has given false testimony, under oath, in order to receive a benefit under the Immigration and Nationality Act.

An applicant must disclose all relevant facts to the Service, including his or her entire criminal history, regardless of whether the criminal history disqualifies the applicant under the enumerated provisions.

Language

You must be able to speak, read, write, and understand basic English; unless you are at least fifty (50) years of age and have been a lawful permanent resident for at least twenty (20) years; or you are at least fifty-five (55) years of age and have been a lawful permanent resident for at least fifteen (15) years; or you have a permanent physical or developmental disability or mental impairment making it impossible for you to meet the English language requirement.

United States Government and History Knowledge

You must be able to demonstrate knowledge and understanding of the fundamentals of U.S. history and principles of government; unless you have a permanent physical or developmental disability or mental impairment making it impossible for you to meet the civics requirement. Or you qualify for "special consideration" because you are at least sixty-five (65) years of age and have been a lawful permanent resident for at least twenty (20) years.

(The USCIS guide has an Eligibility Worksheet for those who want to find out if they qualify for Application of Naturalization.)