(a) Duration. (1) The initial enrollment period is the 7-month period that begins 3 months before the month an individual first meets the eligibility requirements of § 407.10 and ends 3 months after that first month of eligibility.

(2) In determining the initial enrollment period of an individual who is age 65 or over and eligible for enrollment solely because of entitlement to hospital insurance, the individual is considered as first meeting the eligibility requirements for SMI n the first day he or she becomes entitled to hospital insurance or would have been entitled if he or she filed an application for that program.

(b) Deemed initial enrollment period. (1) SSA or CMS will establish a deemed initial enrollment period for an individual who fails to enroll during the initial enrollment period because of a belief, based on erroneous documentary evidence, that he or she had not yet attained age 65. The period will be established as though the individual had attained age 65 on the date indicated by the incorrect information.

(2) A deemed initial enrollment period established under paragraph (b)(1) of this section is used to determine the individual's premium and right to enroll in a general enrollment period if that is advantageous to the individual.