Medicare Advantage coverage does not always begin the day you submit an application. The effective date depends on your enrollment period and when the plan receives a valid request. You need both Part A and Part B before Advantage coverage can take effect.
Common effective dates
| Enrollment situation | Usual start |
|---|---|
| Initial enrollment before Medicare begins | When the required Medicare coverage begins. |
| Initial enrollment after Medicare begins | First of the month after the plan receives the request. |
| October 15–December 7 annual enrollment | January 1 of the following year. |
| January 1–March 31 Advantage open enrollment | First of the month after the request is received. |
| Special enrollment | Depends on the qualifying event and its rules. |
If you add Part B later
The initial plan enrollment opportunity starts three months before you first have both Parts A and B and continues for two months afterward. The plan generally begins the month after the request, subject to the required coverage being in place. Confirm your specific dates rather than using an old three-month-after rule.
Use the correct enrollment period
Advantage open enrollment is for people already in Medicare Advantage; it is not a general opportunity for everyone with Original Medicare to join. Special periods depend on events such as moving or losing qualifying coverage, and their timing varies.
Before using the new card
- Get written enrollment and start-date confirmation.
- Verify the complete plan identifier and year.
- Confirm providers and any authorization for upcoming care.
- Ask how other employer, retiree or supplemental coverage is affected.
Do not cancel other coverage based only on an application confirmation screen. If you receive conflicting dates, contact the plan and Medicare. Keep the application receipt and notices so any enrollment error can be traced without guessing.
Related coverage questions
- When Does Medicare Start? Effective Dates for Parts A and B
- Medicare Advantage: Eligibility, Benefits and Plan Rules
- A Medicare Medical Claim Was Denied: What to Do Next