Medicare enrollment does not start on your birthday. It starts three months before — and that window matters more than most people realize. Miss it, and you could face permanent premium penalties that follow you for the rest of your Medicare years.

This checklist walks you through what to do and when, in the order it actually needs to happen.

3 Months Out: Understand Your Enrollment Window

Your Initial Enrollment Period is seven months long. It opens three months before your birthday month, includes your birthday month, and closes three months after. Enrolling in the first three months means coverage starts the first day of your birthday month. Waiting until your birthday month or later delays when coverage kicks in.

If you are not yet receiving Social Security benefits, Medicare enrollment is not automatic. You need to actively sign up through ssa.gov or your local Social Security office. If you are already receiving Social Security when you turn 65, you are typically enrolled in Parts A and B automatically.

• ✓Confirm whether you will be automatically enrolled or need to apply manually
• ✓Note your exact seven-month enrollment window on your calendar
• ✓Create or log in to your My Social Security account at ssa.gov to check your status
• ✕Don’t assume enrollment is automatic — verify it regardless of your Social Security status

3 Months Out: Clarify Your Current Coverage Situation

Whether you can delay Medicare enrollment without penalty depends entirely on what coverage you have right now. The rules are specific, and the distinction between active employer coverage and retiree or COBRA coverage changes everything.

If you are actively working and covered by a qualifying employer group plan — or covered as a spouse under one — you may be able to delay Part B without penalty. The key word is “active.” Retiree coverage, COBRA, and marketplace plans do not qualify as creditable coverage that lets you defer without penalty.

If you have any doubt about whether your current coverage qualifies for a penalty-free delay, contact your HR department or benefits administrator and ask them directly: “Is my coverage considered creditable for Medicare Part B and Part D purposes?” Get the answer in writing if you can. Assumptions here are expensive.

• ✓Contact your HR or benefits administrator to confirm whether your plan qualifies as creditable coverage
• ✓Ask specifically about both Part B and Part D creditable coverage status
• ✓Find out whether your employer plan coordinates with Medicare or requires Medicare to be primary
• ✕Don’t count retiree coverage, COBRA, or marketplace plans as qualifying for a penalty-free delay

2 Months Out: Make Your List of Doctors and Prescriptions

Before you can compare any Medicare plans meaningfully, you need two things on paper: the names of every doctor or specialist you see regularly, and a complete list of your current prescriptions — including dosages.

These two lists drive almost every plan decision. Whether your doctors are in a given network determines whether a Medicare Advantage plan is viable for you. Whether your medications are on a plan’s formulary determines what your drug costs will actually be. Neither question can be answered without the list in hand.

• ✓Write down every doctor, specialist, and healthcare facility you use regularly
• ✓List every prescription medication with the exact dosage and how often you take it
• ✓Note any upcoming procedures or treatments planned for the next 12 months
• ✓Find out which pharmacy you prefer — formulary coverage can vary by pharmacy as well

2 Months Out: Understand Your Two Main Coverage Paths

Once you have enrolled in Parts A and B, you will need to decide how to fill the gaps Original Medicare leaves. There are two paths, and the right one depends on your health, your finances, and how you use care.

Medicare Advantage (Part C) is a bundled private plan that replaces Original Medicare. Premiums are often low or zero, and drug coverage is usually included. The tradeoff is a provider network and cost-sharing each time you receive care.

Original Medicare with a Medigap Supplement keeps you on government Medicare and adds a private policy that covers deductibles, coinsurance, and gaps. Higher monthly premium, but broader provider access and more predictable costs — useful if you see specialists frequently or travel often.

If you plan to use the Catch Health RX Card for prescription savings, it works alongside most Medicare plan structures and is worth factoring in regardless of which path you choose.

1 Month Out: Compare Real Plans and Enroll

With your doctor and prescription lists ready, you can now run a real comparison. The Medicare Plan Finder at medicare.gov lets you enter your medications and see drug costs across Part D plans. A licensed Medicare agent can run the same comparison across Advantage and Supplement options and show you total estimated annual costs — not just monthly premiums.

Monthly premium is one number. What you actually spend across the year, including copays, deductibles, and drug costs, is the number that matters. Those two figures are rarely the same.

• ✓Use the Medicare Plan Finder at medicare.gov to compare Part D drug plans using your actual prescription list
• ✓Confirm your preferred doctors are in-network for any Advantage plan you are considering
• ✓Ask a licensed agent to show you total annual cost estimates across your top plan options
• ✓Enroll before the end of your Initial Enrollment Period — do not wait for the last week
• ✕Don’t choose based on monthly premium alone — out-of-pocket costs are often the bigger number
• ✕Don’t enroll in a plan without verifying your specific prescriptions are on the formulary

Frequently Asked Questions

What happens if I miss my Medicare enrollment window?
You will face a permanent late enrollment penalty on your Part B premium — 10 percent for each full 12-month period you were eligible but did not enroll. A similar penalty applies to Part D. These surcharges do not go away.

Do I need to enroll in Medicare if I am still working at 65?
It depends on your employer’s plan and company size. In some cases you can defer without penalty; in others, enrolling in Part B is the right move even while working. Your HR department can confirm which situation applies to you.

Can I enroll in Medicare online?
Yes. Most people can apply for Parts A and B through ssa.gov in about 10 minutes. Medicare Advantage, Supplement, and Part D plans are enrolled separately through the plan carrier or a licensed agent.

How do I know which Medicare Supplement plan letter is best?
Supplement plans are standardized — Plan G from one insurer covers the same benefits as Plan G from another. The difference is the premium and the carrier’s financial rating. An independent agent can show you the same plan across multiple carriers to find the best rate.

You Do Not Have to Work Through This Alone

A Catch Health agent can walk through your specific situation — your doctors, your prescriptions, your timeline — and help you enroll in the right coverage before any deadline applies. There is no cost for the help, and no obligation to take any particular plan.