US CITIZENSHIP THROUGH MILITARY SERVICE
Persons in military service to the US may apply for and be naturalized US Citizens through either Section 329 (Military Service during a designated period of hostility) or Section 328 (Naturalization with one or more years of Military Service). When applying for naturalization under Section 329, an N-400 application may be filed as early as one day after having completed honorable service on active duty or in the Selected Reserve of the Ready Reserve. In most cases, the earliest you can submit your application is during basic training. Those in the Delayed Entry Program (DEP) are typically not eligible to apply.
If applying for naturalization under Section 328, an N-400 application may be filed as soon as you become a Lawful Permanent Resident and have completed one year of honorable military service. These provisions are meant to expedite the processing of a naturalization application for those in service to this country. Most military installations have a designated USCIS liaison to help with the application process. Serving in the US Armed forces may also be a viable pathway for those seeking to legalize their status.