8 CFR § 335.6 - Failure to appear for examination.
(a) An applicant for naturalization shall be deemed to have abandoned his or her application if he or she fails to appear for the examination pursuant to § 335.3 and fails to notify USCIS of the reason for non-appearance within 30 days of the scheduled examination. Such notification shall be in writing and contain a request for rescheduling of the examination. In the absence of a timely notification, USCIS may administratively close the application without making a decision on the merits.
(b) An applicant may reopen an administratively closed application by submitting a written request to USCIS within one (1) year from the date the application was closed. Such reopening shall be without additional fee. The date of the request for reopening shall be the date of filing of the application for purposes of determining eligibility for naturalization.
(c) If the applicant does not request reopening of an administratively closed application within one year from the date the application was closed, USCIS will consider that application to have been abandoned, and shall dismiss the application without further notice to the applicant.