The Basics of Medicare: When and How To Sign Up

At A Glance – Choosing the right Medicare coverage can be confusing, but finding the right plan is easier than you think. I cover the basics of how Medicare works and what it costs and include resources to help you with this important decision.

Are you confused by Medicare? What is it? How does it work? What are Parts and Plans? How much will it cost? Do I have to buy it? Medicare can feel complicated. Especially as your mailbox is flooded with ads from companies that have the “Perfect” answer for you! I have good news. You can set all that mail aside for now and plan to throw it all away later. Whew!

Choosing your Medicare coverage is an important decision. When armed with an understanding of the basics and some good resources at your fingertips, you can make the right choice for you!

What is Medicare?

Medicare is a federal health insurance program for:

  • people 65 or older
  • people with certain disabilities younger than 65
  • people with End-Stage Renal Disease (ESRD)

What Are Parts And Plans?

When you hear anyone talk about Medicare, you will probably hear about Parts and Plans. It can be confusing. Here is a breakdown of what is meant by parts and plans.

The “Parts” of Medicare

Medicare has 4 Parts. Parts A, B, C, and D

Medicare Part A:

Part A (hospital insurance) helps pay for inpatient care in a hospital or limited time at a skilled nursing facility (following a hospital stay). Part A also pays for some home health care and hospice care.

Medicare Part B:

Part B (medical insurance) helps pay for doctors and other health care providers, outpatient care, home health care, durable medical equipment, and some preventive services.

Medicare Part C:

Part C, which is now referred to as Medicare Advantage, is private health insurance that you can choose instead of Medicare. You would get your Part A, Part B, and sometimes also Part D all from one insurance carrier.

Medicare Part D:

Part D (drug coverage) is a federal program administered through private insurance companies to help you lower the cost of your retail prescription drugs.

Summary of Parts

Parts A and B are original medicare and you enroll in these on the Social Security website, Parts C and D are purchased from private insurance companies.


Plans refer to supplemental coverage, typically called Medigap Plans, that you can purchase from a private insurance carrier to provide better coverage. These are also named by letters of the alphabet which makes them easily confused with the Parts of Medicare. Right now the popular plans are Plan G and Plan N.

How Does Medicare Work?

Under Original Medicare, you can see any doctor, hospital, health care provider, or facility that accepts Medicare anywhere in the U.S. You do not need a referral and you are not generally responsible for filing your claim.

Typically, any Medicare-approved bill is covered by Original Medicare at 80% and you are responsible for the other 20%. This 20% can be covered by other supplemental insurance you have either bought yourself, such as a Medigap Plan or from an employer plan if you are still working. Keep in mind there is no out-of-pocket maximum for Original Medicare alone.

Medigap vs Advantage Plans

You can purchase insurance in addition to Original Medicare. The main types are Medigap Plans and Medicare Advantage Plans. There is a lot of confusion about Medigap and Medicare Advantage plans because they operate differently and are hard to compare.

You will find a basic description of each below. Be sure to do your homework and research which type of plan is best for you and your healthcare needs. Choosing a Medicare Advantage Plan or a Medigap Plan is one of the most important decisions you will make with Medicare!

Medigap Plans

Medigap Plans are purchased from private insurance companies and work with Original Medicare to help cover your out-of-pocket costs. The combination of Original Medicare and a Medigap plan usually gives you fuller coverage. Medicare pays 80% and a Medigap plan can cover most or all of the 20% depending on which plan you choose. You will be responsible for your Part B deductible, but most costs after that are covered. Part D is not included in Medigap Plans and will need to be purchased separately.

Medigap Pros:

  • You can use any doctor or healthcare provider in the U.S. that accepts Medicare.
  • Lower or no out-of-pocket costs for doctor visits and treatments.
  • No medical underwriting is needed for initial sign-up. Any pre-existing conditions are not considered if you sign up for a Medigap Plan when you first sign up for Medicare.
  • Coverage does not change year to year.

Medigap Cons:

  • Part D is not included.
  • Higher monthly premiums
  • Medical underwriting is required if moving from an Advantage Plan to a Medigap Plan.

Medicare Advantage Plans

A Medicare Advantage Plan is bought from a private insurance company and offers an alternative to Original Medicare. In other words, it replaces Original Medicare. An Advantage Plan includes Part A and Part B coverage. It usually includes Part D and can include things Original Medicare does not cover such as vision, dental, or hearing.

With a Medicare Advantage Plan, you will need to use doctors in the local network. Most Advantage Plans have HMO or PPO networks. You will need to check with all your existing doctors to see if they are part of the network before you sign up for a plan. Be sure to get the full name of the specific plan you are considering when checking with your doctors. It’s not enough to ask, “Do you take Blue Cross?”

You must stay enrolled in Part A and Part B Medicare while enrolled in a Medicare Advantage Plan. Original Medicare pays the Advantage Plan a fee to administer your insurance. You can only enroll or dis-enroll from a Medicare Advantage Plan during certain times of the year, except for the initial enrollment period when you first turn 65. Once enrolled, you must keep that coverage for the remainder of the calendar year.

If your initial choice at age 65 is a Medicare Advantage Plan, be aware that you may need to keep this choice for the long term. Moving to a Medigap Plan after the initial enrollment period will require you to answer health questions and any pre-existing conditions will be considered. It is possible to be denied when trying to move to a Medigap Plan later. [you might remind people what a medigap plan covers]

When choosing a Medicare Advantage Plan, check the plan’s Summary of Benefits carefully to determine what your worst-case scenario costs could be.

Advanatage Plan Pros:

  • Advantage Plans can offer extra benefits that Original Medicare doesn’t cover like vision, dental, and hearing.
  • You pay for services as you use them through co-pays and co-insurance. If you are healthy, your ongoing costs can be lower.
  • One card to present to a healthcare provider.
  • The monthly premiums can be lower.

Advantage Plan Cons:

  • You are limited to in-network healthcare providers.
  • You may not find an in-network provider away from your home area.
  • If you choose an Advantage Plan when you first sign up for Medicare at age 65, you may need to keep this coverage for the long term. You can be turned down for a Medigap Plan if you are not healthy enough.
  • Advantage Plan benefits may change every year.
  • Prior authorizations may be required for certain tests or procedures and many HMO plans require a referral from your primary care doctor before seeing a specialist.
  • While premiums are lower, the back-end costs such as copays and coinsurance may cost more.
  • The plans are hard to compare because they are not standardized.

You can see there are a lot of things to consider when choosing between a Medigap Plan or an Advantage Plan. What’s right for your neighbor may not be right for you. The decision should be based on your budget, healthcare needs, and where you live.

I would strongly suggest you use an independent insurance agent who is familiar with the plans available in your area. They can help you evaluate the choices and navigate any nuances and exceptions that may apply to you. Using an independent agent does not cost you anything. They are paid by Medicare, so take advantage of their expertise.

Boomer Benefits has a great video on the pros and cons of Medigap and Medicare Advantage Plans. Watch here.

When Do You Sign Up?

You are eligible to sign-up for Original Medicare (Parts A and B) when you turn 65. To be eligible for Part C or Medicare Advantage, you must first be enrolled in both Medicare Parts A and B. You must also be enrolled in Medicare Parts A and B to be eligible for Part D drug coverage.

If you are receiving Social Security, you will be automatically enrolled in Original Medicare at age 65 and your medicare card will show up in the mail shortly before your 65th birthday. If you are not receiving Social Security, you can enroll during a 7-month window called the Initial Enrollment Period. This includes 3 months prior to the month you turn 65, your birthday month, and 3 months after your birthday month.

How Do You Sign Up?

Sign up for Original Medicare at your Social Security office or online at the Social Security website, Online is the easiest and fastest way to sign up. You’ll need to create your secure “my Social Security” account to sign up. Medicare provides your coverage, but you’ll sign up through Social Security.

Medigap Plans, Medicare Advantage Plans, and Part D drug coverage are purchased from private insurance companies. You will need to contact an independent insurance agent to determine which plans are available in your zip code. If you purchase a Medicare Advantage Plan, check to see if it includes Part D. If it doesn’t or you are purchasing a Medigap Plan, you will need to purchase separate Part D coverage.

Medigap plans are standardized in most states. Currently, the popular plans are Plan G and Plan N. Plan G pays for your Medicare Part A hospital deductible, copays, and coinsurance. It also covers the 20% that Medicare Part B doesn’t cover minus your Part B deductible. Plan N covers less than Plan G, but usually offers lower premiums.

How Much Does It Cost?

For most Americans, Part A is free when you turn 65. This has been prepaid with your payroll FICA taxes. If you have paid FICA taxes for 40 quarters or are married to someone who did, your part A is free. See the chart below for the breakdown of Part A costs.

The base cost of Part B is set by Medicare once a year. For 2023, Part B costs $164.90/month with a yearly deductible of $226. If you are currently receiving Social Security, your Part B premium will be deducted from your SS check. If not, you will receive a bill.

2023 Medicare Cost For Part A and B

Part ALess Than 30 Credits = $50630-39 Credits = $27840+ Credits = $0
Part B$164.90
Part B Deductible$226.00/year

The total cost of Part B depends on two things, when you sign up and your income level. Most people pay the base cost. If you delay signing up for Part B, you will pay a monthly penalty and the penalty goes up the longer you wait. Another factor is your income. Higher earners will pay more. This additional cost is called the Income-Related Monthly Adjustment Amount or IRMAA. You can find a description of IRMAA below.

Part D Cost

The cost of Part D is not set by the federal government, but by the insurance carrier within Medicare guidelines. When comparing drug plans, don’t just pick the plan with the lowest premium. You will want to compare total drug costs which will include monthly premiums, deductibles, and co-pays. Make a list of the prescription drugs you currently take and go to and use their plan finder tool. It will compare drug plans in your local area.

As with Medicare Part B, signing up late for Part D can cost you a penalty that you will pay for as long as you have Part D coverage, even if you switch plans. Also, Part D is subject to IRMAA.


Who the heck is IRMAA and what does she have to do with Medicare!! IRMAA (Income-Related Monthly Adjustment Amount) is not a she, it is a surcharge you will pay if you have a high income. It is an increase to Medicare Part B and Part D standard monthly premiums and is determined by the Social Security Administration.

IRMAA is based on your Modified Adjusted Gross Income or MAGI from two years ago. So the IRMAA amount you would pay in 2023 is calculated on your MAGI from your 2021 Federal tax return. The IRMAA calculation is based on a Medicare-specific form of MAGI. (MAGI for IRMAA is different than MAGI for non-healthcare purposes.) This article from Stay Wealthy explains what is included in IRMAA MAGI.

The surcharge you pay is calculated on a graduated scale, so the more you make, the more IRMAA you pay. The chart below shows the surcharge for Married Filing Joint (MFJ) and for Single Filers based on 2021 MAGI. These amounts would be added to your Part B and Part D premiums.

Your 2021 MAGI Income was:IRMAA Surcharge
MFJSinglePart BPart D
$194,000 or less$97,000 or less —– —–
$194,001 – $246,000$97,001 – $123,000$65.90$12.20
$246,001 – $306,000$123,001 – $153,000$164.80$31.50
$306,001 – $366,000$153,001 – $183,000$263.70$50.70
$366,001 – $749,999$183,001 – $499,999$362.60$70.00
$750,000 or more$500,000 or more$395.60$76.40

There are ways to reduce or avoid IRMAA. Since IRMAA is based on MAGI, you can reduce the surcharge if you can reduce your MAGI. There are several ways to reduce your MAGI, such as charitable giving or using tax-efficient investments or withdrawals. Speak to your tax advisor about these strategies.

IRMAA can possibly be eliminated if you have experienced a life-changing event as defined by the Social Security Administration. One of these life-changing events is work stoppage or reduction, i.e. retirement. (Here is a full list of life-changing events.) If you experience one of these, you will need to file Form SSA-44 to start the reconsideration process. Because IRMAA is a two-year look-back, you will need to file Form SSA-44 for 2 years. Don’t assume the first filing will take care of year two.

Keep in mind that IRMAA is calculated every year, not just when you initially sign up for Medicare.

My Personal Experience

My husband Stephen and I are both on Medicare. We received the onslaught of mail prior to each of us turning 65. At first, we thought we needed to save it all and look at each one. Stephen did hours of research only to find out we have a limited number of options in our county.

We used an independent insurance agent to help evaluate the plans available to us and which was best. We chose Medigap Plan G and a Part D plan.

Here is how we made our initial decisions. Both of us have pre-existing conditions. One of us uses healthcare providers more than the other, so at first, Medigap seemed right for one and an Advantage plan for the other. This combination would have provided the lowest out-of-pocket costs initially. But, we decided to purchase Medigap for both of us. The reason is our out-of-pocket costs with Medicare Advantage could be higher in the future if the pre-existing condition became an issue again. Changing to Medigap later might not be possible, so we eliminated that risk and bought the Medigap Plan G. We may pay a little more per month now, but our future risk is limited.

We also purchased a Part D plan (to avoid the penalty), but we chose the cheapest one. Neither of us uses expensive prescription drugs. We checked with our local pharmacy’s drug plan and with GoodRx. Most of the time, the cost of our prescriptions is lower with GoodRx than with our Part D coverage. Now when we fill a prescription, we always have them check all three options and then use the cheapest one. It is rarely our Part D coverage, but again, we have Part D to avoid the penalty.

So far, we have been happy with our choices. Our current monthly cost for Part B, Plan G, and Part D for the two of us is $590.19. We have also purchased a dental discount plan for one person at $55/month.


Key Takeaway – Medicare can feel complicated but armed with basic information and some great resources, this important decision can be easier than you think. The most important point is to not delay in signing up when you turn 65.

Assignments – If you are approaching 65, find a good independent insurance agent to help you evaluate your options and look through the Medicare website to educate yourself before you decide.

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