If you recently become enrolled in Medicare Part A or Part C, or are eligible for premium-free Medicare Part A, you are considered to have another source of minimum essential coverage, and will not be eligible for premium tax credits through Pennie.
If you are enrolled in coverage through Pennie, you can keep it until your Medicare coverage starts. However, you will want to terminate your Pennie coverage as soon as you enroll in Medicare to avoid paying full-price for a plan through Pennie.
In most cases, it's to your advantage to sign up for Medicare when you're first eligible. Once you’re eligible for Medicare, you’ll have an Initial Enrollment Period to sign up for Medicare. For most people, the Initial Enrollment Period starts 3 months before their 65th birthday and ends 3 months after their 65th birthday.