Chapter 6 - Jurisdiction, Place of Residence, and Early Filing | USCIS
"Although an applicant may file early according to the 90 day early filing provision, the applicant is not eligible for naturalization until he or she has reached the required five-year period of continuous residence as a lawful permanent resident (LPR)."
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D. 90-Day Early Filing Provision (INA 334)
An applicant filing under the general naturalization provision may file his or her application up to 90 days before he or she would first meet the required 5-year period of continuous residence as an LPR.[14] Although an applicant may file early according to the 90 day early filing provision, the applicant is not eligible for naturalization until he or she has reached the required five-year period of continuous residence as a lawful permanent resident (LPR).
USCIS calculates the early filing period by counting back 90 days from the day before the applicant would have first satisfied the continuous residence requirement for naturalization. For example, if the applicant would satisfy the five-year continuous residence requirement for the first time on June 10, 2010 USCIS will begin to calculate the 90-day early filing period from June 9, 2010. In such a case, the earliest that the applicant is allowed to file would be March 12, 2010 (90 calendar days earlier).
In cases where an applicant has filed early and the required three month period of residence in a state or service district falls within the required five-year period of continuous residence, jurisdiction for filing will be based on the three-month period immediately preceding the examination on the application.[15]"