When to Enroll in Medicare

Confirm your situation with Social Security.

If you turn 65 in 2027, your Initial Enrollment Period lasts seven months: the three months before your birthday month, your birthday month and the three months after. Signing up during the first three months means your coverage starts on the first day of your birthday month.

Medicare Advantage, also called Part C, is a way to get your Medicare benefits through a private insurance company approved by Medicare. The plan covers everything Original Medicare Part A and Part B cover, except hospice care, which Original Medicare still pays. Most plans also include Part D drug coverage, and many may add extras such as routine dental, vision and hearing benefits.

In exchange, Medicare Advantage plans generally use networks of doctors and hospitals, and may require referrals or prior authorization for some services. Every Medicare Advantage plan has a yearly out-of-pocket maximum for covered medical care, which Original Medicare does not have. You keep paying your Part B premium, plus your plan’s premium if it has one.

If your income and savings are limited, two programs can cut your Medicare costs sharply:

Those who are eligible for Medicare along with full Medicaid might also have the option of enrolling in a Dual Special Needs Plan. Learn more about help for low-income Part D beneficiaries.

Plans must send the Annual Notice of Change by September 30. It is the single most useful document you get each fall, because it tells you exactly how your plan changes on January 1.

Outside the fall and early-year windows, you generally need a Special Enrollment Period to change plans. Common reasons include:

Each Special Enrollment Period has its own time limit, so act as soon as the event happens.

Most Medicare Advantage plans require prior authorization for some services, such as certain surgeries, advanced imaging, skilled nursing stays and some drugs. Your doctor usually requests it, but ask whether a planned service needs approval so a denial does not surprise you.

If a request is denied, you or your doctor can appeal. Medicare rules set deadlines for plans to decide, with faster deadlines when waiting could seriously harm your health.

Every Medicare Advantage plan covers emergency care and urgent care anywhere in the U.S., in or out of network, and you do not need prior approval for an emergency. Routine care away from home is a different story: HMOs generally do not cover it, while PPOs cover out-of-network care at a higher cost.

If you spend months away from home each year, ask each plan how it handles care in your second location. It is one of the most common reasons people switch plans mid-year.

If your plan denies a service, a drug or payment for care, you have the right to appeal. The plan’s denial notice explains how. There are several levels of appeal, starting with the plan and moving to independent reviewers.

For problems that are not about coverage, such as customer service or wait times, you can file a grievance with the plan. You can also contact 1-800-MEDICARE or your State Health Insurance Assistance Program for help.

The Part B premium is the one big number not released with the plans. CMS normally announces it in November. The 2026 Medicare Trustees Report projects a 2027 standard premium of about $209.50 a month and a deductible of about $292, up from $202.90 and $283 in 2026. You keep paying it with Medicare Advantage.

If you miss the Annual Enrollment deadline, your current plan renews automatically for 2027, with the changes in your Annual Notice of Change. If you are in Medicare Advantage, you get one more chance from January 1 to March 31, 2027, to switch Medicare Advantage plans or return to Original Medicare and join a Part D plan.

Many Medicare Advantage plans may cover telehealth visits for some services, sometimes at a lower copay than an office visit. Telehealth is convenient for follow-ups and minor issues, but it does not replace confirming that your regular doctors are in network.

Special Needs Plans (SNPs) are Medicare Advantage plans built for specific groups. Benefits, networks and drug lists are designed around the members they serve, and many include care coordinators. For 2027, Special Needs Plans are one of the few areas where large insurers are adding plans, even as they cut PPOs.

Medicare rates every Medicare Advantage and Part D plan from 1 to 5 stars each fall, based on things like preventive care, how well the plan manages chronic conditions, member complaints, customer service and drug pricing accuracy. The ratings are shown in Medicare Plan Finder.

Sometimes a drug you take is not on a plan’s 2027 formulary, or it carries a rule like prior authorization. You still have options:

See steps to appeal a Medicare Part D denial.

Tier structures vary by plan. Check each plan’s formulary.

Your six-month Medigap Open Enrollment Period starts the first month you are both 65 or older and enrolled in Part B. It happens only once and cannot be restarted. During it, insurers must sell you any Medigap plan they offer in your state, at the same price as people in good health.

If you keep working past 65 with employer coverage and delay Part B, your Medigap Open Enrollment Period waits until you enroll in Part B. Enrolling in Part B early, when you do not need it, starts the clock and can waste this protection.

If you have coverage from a current employer, you may not need Medigap yet, and delaying Part B can preserve your Medigap Open Enrollment Period for later. Retiree coverage is different: it may work like a supplement, so compare it with Medigap before dropping it, because you may not be able to get retiree coverage back.

When employer or union coverage that pays after Medicare ends, you generally have a guaranteed issue right to buy certain Medigap plans.

If you buy Medigap during your open enrollment period or with a guaranteed issue right, you generally cannot be denied or charged more for health conditions. However, if you did not have creditable coverage before, an insurer may impose a waiting period of up to six months before covering costs for a pre-existing condition. Prior creditable coverage reduces or removes that waiting period.

If you replace one Medigap policy with another, you generally get 30 days to decide whether to keep the new policy. Pay the premiums for both during that time, and do not cancel your old policy until you are sure about the new one.

If a quote includes an introductory discount, ask what the premium becomes after it ends.

If you have full Medicaid, you generally do not need Medigap, and insurers generally cannot sell you a policy that duplicates Medicaid benefits. If you qualify for a Medicare Savings Program, it may pay your Part B premium and, in some cases, deductibles and coinsurance; check whether a Medigap policy still adds value for you.

A Medicare Supplement plan is built to cover the gaps in Original Medicare. These are the costs it can pick up:

Federal law sets exactly what each plan letter covers, so the same letter has the same benefits from every insurer in your state.

*Plans C and F can only be bought by people who were eligible for Medicare before January 1, 2020. **Plans K and L have a yearly out-of-pocket limit that Medicare sets each year; after you reach it, the plan pays 100% of covered services for the rest of the year. ***Plan N pays all Part B coinsurance except copays of up to $20 for some office visits and up to $50 for emergency room visits that do not lead to an inpatient admission. Massachusetts, Minnesota and Wisconsin standardize their plans differently.

You do not have to compare plans alone, and you should not have to pay for help. These are the free options:

Before any call, have your Medicare card, your list of drugs and doses, your doctors and your preferred pharmacies ready. It turns a long conversation into a short one.