Permanent residents in the United States must meet certain standards prior to obtaining citizenship. Generally, permanent residents must prove that they were residents of California or another state for a continuous period of five years. They must also prove that they were physically in the country for 30 months in the five-year period before applying or 18 months within the last three years for qualified spouses of citizens.
Those who leave the United States for more than six months may disrupt their continuous residence in the country. However, it may possible to prove otherwise if the absence was less than 12 months. In addition to those requirements, it is necessary to prove that an applicant has resided in the area where they applied for at least three months prior to applying. There are several exceptions to the rules for those who may have left the country for military or other specific causes.
For instance, those who worked abroad for a government contractor may preserve their continuous residency. The same may be true for those who worked for a public international organization during the time in which they otherwise would have their residency disrupted. Those affiliated with certain groups under the International Immunities Act may be eligible for an exception to naturalization requirements.
Permanent residents who wish to become United States citizens may wish to talk to an immigration attorney to discuss their case. An attorney may be able to provide advice regarding whether or not an individual is permitted to leave the country without jeopardizing their citizenship claim. An attorney might also be able to help an individual clarify an individual’s immigration status if he or she has left the country for a period of six months or more.
Source: USCIS, “Continuous Residence and Physical Presence Requirements for Naturalization“, December 31, 2014