Enrolling in Medicare is one of the most important financial decisions you will make in retirement, and the process begins well before your 65th birthday. Missing deadlines can result in permanent premium penalties and gaps in coverage. This month-by-month timeline helps you stay organized so that everything falls into place by the time your benefits start.
12 Months Before You Turn 65: Start Your Research
A full year before your birthday is the right time to begin gathering information. You do not need to make any decisions yet, but understanding the landscape will save you stress later.
- Learn the basics of Medicare. Familiarize yourself with the four parts: Part A (hospital insurance), Part B (outpatient and doctor services), Part C (Medicare Advantage), and Part D (prescription drug coverage).
- Make a list of your current medications, including dosages. You will need this later when comparing Part D and Medicare Advantage formularies.
- Identify your doctors and specialists. Note which providers you want to continue seeing and whether they participate in Medicare.
- Start thinking about budget. Research the current Part B premium, typical Medigap premiums in your state, and the cost range for Medicare Advantage plans in your area.
9 Months Before: Evaluate Your Employer Coverage
If you are still working and covered by an employer group health plan, this is the time to have a detailed conversation with your benefits department.
- Ask whether your employer plan is considered creditable coverage for both Part B and Part D purposes. For Part B, employer coverage counts as creditable only if the employer has 20 or more employees. For Part D, ask whether your drug benefit is at least as comprehensive as a standard Part D plan.
- Find out whether you need to enroll in Part A and Part B now or can delay. If your employer has 20 or more employees, you can usually delay Part B without penalty and rely on your employer plan as primary. If your employer has fewer than 20 employees, Medicare becomes your primary insurer at 65, and you should enroll in Part B on time.
- Understand how Medicare and your employer plan will coordinate if you enroll in both simultaneously. In most cases with large employers, your group plan pays first and Medicare pays second.
- Ask about retiree benefits. Some employers offer retiree health coverage that works alongside Medicare. Find out the details so you can factor this into your decision.
6 Months Before: Contact Social Security
Your Initial Enrollment Period (IEP) for Medicare spans seven months — the three months before your birthday month, your birthday month itself, and the three months after. At the six-month mark, you are approaching the start of this window.
- If you are already receiving Social Security benefits, you will typically be enrolled in Part A and Part B automatically. You should receive your Medicare card in the mail about three months before you turn 65. Review it for accuracy.
- If you are not yet collecting Social Security, you will need to actively sign up. You can apply online at ssa.gov, call Social Security at 1-800-772-1213, or visit your local office. Applying early in your IEP ensures your coverage starts on the first day of your birthday month.
- If you plan to delay Part B due to creditable employer coverage, you can enroll in Part A only. Make sure to document your employer coverage in case you need to prove continuous creditable coverage later.
3 Months Before: Your IEP Opens — Make Key Decisions
This is when the clock officially starts. The decisions you make during this period determine the shape of your Medicare coverage.
Original Medicare vs. Medicare Advantage
You have two main paths:
- Original Medicare (Parts A and B) with optional Medigap and Part D add-ons. This path gives you the broadest provider access — any doctor or hospital in the country that accepts Medicare. You pay deductibles and coinsurance, but Medigap policies can cover most or all of those costs.
- Medicare Advantage (Part C) from a private insurer. These plans bundle Part A, Part B, and usually Part D into a single plan, often with additional benefits like dental, vision, and hearing. However, they use provider networks (HMO or PPO), and your costs depend on staying in network.
Consider your priorities: Do you value provider choice and willingness to pay higher premiums for predictability (lean toward Original Medicare plus Medigap)? Or do you prefer lower premiums and extra benefits with the trade-off of network restrictions (lean toward Medicare Advantage)?
Part D Selection
If you choose Original Medicare, you will likely want a standalone Part D plan for prescription drug coverage. Compare plans based on:
- Monthly premium
- Annual deductible
- Formulary — make sure your medications are covered and check which tier they fall on
- Pharmacy network — confirm your preferred pharmacy is in-network
- Coverage in the gap phase — some plans offer additional coverage beyond the standard benefit
If you choose Medicare Advantage, drug coverage is usually built in, so a separate Part D plan is not needed.
Medigap Open Enrollment
If you opt for Original Medicare, your Medigap Open Enrollment Period begins the month you turn 65 and are enrolled in Part B. For the next six months, insurers must sell you any Medigap policy they offer regardless of your health status, with no medical underwriting. This is your best — and in most states, your only — guaranteed opportunity to purchase Medigap coverage at standard rates.
Popular Medigap plans to compare:
- Plan G — covers nearly all out-of-pocket costs except the Part B deductible
- Plan N — lower premiums with small copays for office visits and emergency room visits
- Plan F — the most comprehensive option, but available only to those who became eligible for Medicare before January 1, 2020
Your Birthday Month: Confirm Everything Is Active
By now, your enrollment should be processed. During your birthday month:
- Verify your Medicare card has arrived and the information is correct.
- Confirm your chosen plan (MA, Part D, or Medigap) is active by calling the insurer.
- Schedule your Medicare Welcome Visit — a one-time preventive visit covered at no cost within the first 12 months of Part B enrollment.
- Set up your MyMedicare.gov account to manage claims, view your Medicare Summary Notice, and access plan information online.
1 to 3 Months After: Wrap Up Loose Ends
Your IEP extends three months past your birthday month. If you have not completed enrollment, act immediately — the later you enroll within the IEP, the later your coverage start date:
- Enroll in month 1 after your birthday: coverage starts the following month
- Enroll in month 2: coverage starts two months later
- Enroll in month 3: coverage starts three months later
After everything is in place:
- Notify your previous insurer if you are transitioning from employer coverage, COBRA, or a marketplace plan.
- Update your providers with your new insurance information.
- Fill prescriptions under your new Part D or MA plan and verify costs match expectations.
- File away important documents — your Medicare card, plan materials, formulary list, and any creditable coverage letters — in a safe, accessible location.
Final Thoughts
Turning 65 and enrolling in Medicare does not have to be overwhelming if you give yourself enough lead time. Starting your research a year in advance, checking employer coverage at nine months, contacting Social Security at six months, and making plan decisions when your IEP opens at three months gives you a clear, manageable path. The enrollment choices you make now will shape your healthcare costs and access for years to come, so take the time to get them right.