Quick answer: your Medicare Initial Enrollment Period lasts seven months: the three months before the month you turn 65, your birthday month, and the three months after. Sign up in the three months before your birthday month and coverage starts on the first day of your birthday month. Sign up later in the window and coverage starts the first day of the month after you sign up. If you already get Social Security benefits, you are enrolled in Parts A and B automatically. Start planning about six months before your birthday so you have time to compare Medigap, Medicare Advantage and Part D options.
Turning 65 brings a lot of mail, a lot of phone calls and a deadline that many people do not realize is there. The decisions you make in the months around your birthday shape what you pay for Medicare for years, and some mistakes, such as missing Part B without other qualifying coverage, carry penalties that last as long as you have Medicare.
This checklist breaks the process into months, starting half a year before your birthday. It assumes you qualify for Medicare at 65; people who qualify earlier because of a disability follow different timing. For the full background on eligibility, costs and coverage choices, see our Medicare guide: eligibility, enrollment, costs and choosing coverage.
Rules and figures below come from Medicare.gov, the Social Security Administration (SSA) and CMS, checked October 2026. Your situation may differ, especially if you are still working. This is general information, not personalized insurance advice; free one-on-one counseling is available from your State Health Insurance Assistance Program (SHIP).
Before You Start: Three Facts That Shape the Timeline
A few rules decide which steps apply to you.
Your Initial Enrollment Period
According to Medicare.gov, most people can first sign up for Part A and Part B during a seven-month Initial Enrollment Period that starts three months before the month they turn 65 and ends three months after. Our detailed explainer on when to sign up for Medicare walks through the window with examples.
There is one quirk: if your birthday falls on the first of the month, Medicare.gov says your eligibility and your window start one month earlier.
Automatic versus manual enrollment
If you have been receiving Social Security or Railroad Retirement Board benefits for at least four months before you turn 65, you are enrolled in Part A and Part B automatically, and your Medicare card arrives in the mail about three months before your birthday. Everyone else has to sign up, usually through Social Security.
Medicare at 65 is not Social Security at 65
Full retirement age for Social Security is later than 65 for anyone born after 1937, and it is 67 for people born in 1960 or later, according to the SSA. Many people delay Social Security but still need to sign up for Medicare at 65. Delaying your retirement benefit does not delay your Medicare deadline.
Six Months Before Your Birthday Month
This is the planning stage. Nothing needs to be filed yet, but the choices you make now drive everything later.
Check how you are covered today
- Job-based coverage through your own or your spouse’s current work? If the employer has 20 or more employees, you may be able to delay Part B without penalty. Ask your benefits office how the plan works with Medicare.
- COBRA, retiree coverage, a Marketplace plan or no coverage? Plan to enroll in Parts A and B during your Initial Enrollment Period. These kinds of coverage do not protect you from the Part B late enrollment penalty.
Watch out for HSA contributions
If you contribute to a health savings account, the IRS does not allow contributions once you are enrolled in any part of Medicare. Because premium-free Part A can be backdated up to six months when you sign up after 65, people who delay Medicare often stop contributing six months before they enroll. Ask a tax professional about your case.
Create your online accounts
Set up a my Social Security account at SSA.gov. Once you have a Medicare number, you can also create a Medicare.gov account to compare plans with your own drug list.
Start a simple list
Write down your prescriptions (name, dose and how often you take them), your doctors, the hospital you prefer and your pharmacy. You will use this list to compare plans.
Four to Five Months Before
Use this time to learn the main choice you will face.
Original Medicare plus Medigap and Part D
Original Medicare (Parts A and B) lets you see any provider in the U.S. that accepts Medicare. You can add a Medicare Supplement Insurance (Medigap) policy to cover most of what Original Medicare leaves you to pay, and a standalone Part D plan for drugs.
Medicare Advantage
A Medicare Advantage plan (Part C) is offered by a private company approved by Medicare. It replaces Original Medicare for most purposes, usually includes drug coverage, and has a yearly out-of-pocket limit, but generally uses a network.
Our comparison of Medicare Advantage vs Medigap sets out the trade-offs in detail. If you are leaning toward Medigap, our breakdown of Medigap Plan G vs Plan N compares the two most popular plans for new enrollees.
Know the 2026 costs
CMS lists the standard Part B premium at $202.90 a month in 2026 and the Part B deductible at $283. Most people pay no premium for Part A. Higher earners pay an income-related monthly adjustment amount on top of Part B and Part D premiums; our guide to Medicare premiums and IRMAA explains who pays more and how to appeal.
Three Months Before: Your Window Opens
Your Initial Enrollment Period begins. Signing up now gives you the earliest possible start date.
If you are enrolled automatically
Watch for your red, white and blue Medicare card. It should arrive about three months before your birthday month. Part B is optional for people enrolled automatically; the card package explains how to decline it, but declining is risky unless you have qualifying job-based coverage.
If you need to sign up
Apply through Social Security. The SSA lets you apply online, by phone at 1-800-772-1213 or at a local office. Applying online takes most people less than half an hour.
Coverage start dates
Medicare.gov describes how start dates work:
| When you sign up | When Part A and Part B start |
|---|---|
| Any of the 3 months before your birthday month | First day of your birthday month |
| During your birthday month | First day of the next month |
| Any of the 3 months after your birthday month | First day of the month after you sign up |
Signing up early avoids a gap between your current coverage and Medicare.
Two Months Before: Choose Your Additional Coverage
With your Part A and Part B start date known, pick the coverage that goes with it.
Medigap timing
Your six-month Medigap Open Enrollment Period starts the first month you are 65 or older and enrolled in Part B. During that window, Medicare.gov explains, insurers cannot refuse to sell you any Medigap policy they offer or charge more because of health problems. After it ends, most states allow insurers to use medical underwriting. Many insurers accept applications up to six months before your Part B start date, which lets the policy begin the same day as Part B.
Medicare Advantage and Part D timing
You can join a Medicare Advantage plan or a Part D drug plan during your Initial Enrollment Period. Medicare.gov notes that if you join before your Part A and Part B start, plan coverage begins the same day.
Compare plans with your list
Open Medicare Plan Finder on Medicare.gov, enter your drugs and pharmacy, and compare estimated yearly costs, not just premiums. For drug plans, check each drug’s tier, any prior authorization or step therapy rules, and remember the 2026 out-of-pocket cap of $2,100 on covered Part D drugs.
One Month Before
Tie up loose ends so nothing lapses.
Line up the switch from current coverage
If you are leaving a job plan, COBRA or a Marketplace plan, pick an end date that matches your Medicare start date. Marketplace subsidies generally end once you are eligible for premium-free Part A, so cancel the Marketplace plan for the right date rather than letting it continue.
Confirm your providers
Call your doctors to make sure they accept Medicare, or that they are in network for the Medicare Advantage plan you chose. Confirm that your pharmacy is in your drug plan’s network, and preferred if possible.
Set up premium payment
Most people who get Social Security have the Part B premium deducted from their benefit. If you are not collecting benefits yet, Medicare bills you directly. Medigap, Part D and some Medicare Advantage plans bill separately; set up automatic payment so coverage does not lapse.
Your Birthday Month
If you signed up during the three months before, your coverage starts on the first of this month.
Check your cards
You should now have your Medicare card and, if you chose them, cards for your Medigap policy, drug plan or Medicare Advantage plan. Carry the ones your plans ask you to show. Medicare Advantage members generally use the plan card instead of the red, white and blue card.
Still need to sign up?
You can still enroll this month or in the three months that follow. Coverage will start the first day of the month after you sign up, so act quickly.
One to Three Months After
These are the last months of your Initial Enrollment Period.
Last chance to enroll without a penalty
If you do not have coverage based on current employment, the end of this window is your deadline. Medicare.gov’s penalty page says that missing it can mean waiting until the General Enrollment Period (January 1 to March 31), with coverage starting the month after you sign up, plus a Part B penalty of 10% for each full 12-month period you could have had Part B but did not. Part D has a separate penalty of 1% of the national base beneficiary premium for each month you went without creditable drug coverage; that base premium is $38.99 in 2026.
Book your Welcome to Medicare visit
Part B covers a one-time “Welcome to Medicare” preventive visit within the first 12 months you have Part B, according to Medicare.gov. After that, Part B covers a yearly wellness visit.
Fill a prescription early
Use your new drug coverage before you run low on any medication, so you have time to fix any formulary or pharmacy problems.
Your First Fall on Medicare
Medicare decisions are not one-time choices.
Annual Enrollment Period
Every year from October 15 to December 7, you can change Medicare Advantage or Part D plans, or switch between Original Medicare and Medicare Advantage, with changes starting January 1. Read your plan’s Annual Notice of Change each September.
Medigap is different
Medigap does not have an annual switching period at the federal level. If you leave Medigap later, you may not be able to buy it back without medical underwriting, so weigh that before changing paths.
Keep your records
Save your enrollment confirmations, creditable coverage notices from past employers, and any letters from Social Security. They can prove your eligibility if a penalty is ever charged in error.
One-Page Turning 65 Checklist
| When | What to do |
|---|---|
| 6 months before | Review current coverage, stop HSA contributions if relevant, create a my Social Security account, list drugs and doctors |
| 4-5 months before | Learn Original Medicare plus Medigap vs Medicare Advantage; check 2026 costs |
| 3 months before | Window opens; apply through Social Security unless enrolled automatically |
| 2 months before | Choose Medigap or Medicare Advantage and a Part D plan; compare on Plan Finder |
| 1 month before | Align end of old coverage, confirm providers, set up payments |
| Birthday month | Coverage starts if you signed up early; check cards |
| 1-3 months after | Last months of your window; book Welcome to Medicare visit; test your drug plan |
| Each fall | Review your plan during the October 15 to December 7 window |
Free help is available through your State Health Insurance Assistance Program at SHIPhelp.org or by calling 1-800-MEDICARE (1-800-633-4227). If you want a plain-English refresher on what each part covers before you start, read our explainer on Medicare Parts A, B, C and D.
Frequently Asked Questions
When should I sign up for Medicare if I am turning 65?
During your seven-month Initial Enrollment Period. Signing up in the three months before your birthday month means coverage starts on the first day of your birthday month.
Do I have to sign up if I am already getting Social Security?
No. If you have received Social Security or Railroad Retirement Board benefits for at least four months before you turn 65, you are enrolled in Parts A and B automatically and your card arrives about three months before your birthday.
Can I delay Medicare if I am still working?
Often, yes, if you or your spouse have group coverage from current employment with an employer of 20 or more employees. With a smaller employer, or with COBRA, retiree or Marketplace coverage, you generally need to enroll at 65.
When is the best time to buy a Medigap policy?
During your six-month Medigap Open Enrollment Period, which starts the first month you are 65 or older and have Part B. Insurers cannot deny you or charge more for health reasons during that window.
What happens if I miss my Initial Enrollment Period?
You may have to wait for the General Enrollment Period from January 1 to March 31 and pay a lifetime Part B penalty of 10% for each full year you went without Part B, unless you qualify for a Special Enrollment Period.
Sources
- Medicare.gov, When does Medicare coverage start, and How do I sign up for Medicare.
- Medicare.gov, Avoid late enrollment penalties (Part B and Part D examples, 2026 base beneficiary premium).
- Medicare.gov, Medigap Open Enrollment Period and preventive visit coverage.
- Social Security Administration, When to sign up for Medicare; full retirement age chart.
- CMS, 2026 Medicare Parts A and B premiums and deductibles fact sheet.
- IRS Publication 969, Health Savings Accounts and Other Tax-Favored Health Plans.
