Another key requirement for naturalization in the United States is that the applicant be physically present in the U.S. for thirty months within the five year period before applying, OR, in the case of qualified spouses of U.S. citizens, physically present in the U.S. for eighteen months within the three year period before applying.  This time need NOT be continuous. To meet this requirement the applicant is permitted to aggregate time spent in the U.S. Therefore, even if one takes frequent trips outside the United States during the five year period before filing his application, as long as a total of 30 months (or one-half of the five year period) is spent in the U.S., he will meet this requirement.