00cefaae_cial_Enrollment_Periods__SEPs___When_does_my_coverage_begin_
[SEP Event] Having a change in income or household status that affects eligibility for premium tax credits or cost-sharing reductions (for people already enrolled in Marketplace coverage) [When can I enroll?] Up to 60 days after the event [When does my coverage begin?] 
If you enroll within first 15 days of the month, your coverage begins on the first day of the month after you enroll. —or— If you enroll on or after the 16th day of the month, your coverage begins on the first day of the next month after you enroll.
Health First Individual | Special Enrollment Periods (SEPs)
When does my coverage begin?