For a participant, certification for initial eligibility begins not sooner than the first day of the month of application. A participant’s eligibility under Regulation .03 of this chapter will end as of the: End of a 12 month certification period; Date eligibility is determined in another Medicaid coverage group; Date the participant ceases to qualify under the requirements of Regulation .03A of this chapter; Beginning of the month in which the participant is enrolled in Medicare; or Date a participant becomes an inmate in a public institution.