When you turn 65, you have a seven-month window to enroll in Medicare. For some people, enrollment happens automatically. For others, you need to sign up yourself. The process is straightforward once you know which category you fall into and what deadlines to hit.
Check Whether You’re Automatically Enrolled
If you’re already receiving Social Security benefits when you turn 65, you’ll be automatically enrolled in Part A (hospital coverage). Your Medicare card will arrive in the mail about three months before your 65th birthday. You don’t need to do anything for Part A in this case.
If you’re not yet collecting Social Security, you won’t be automatically enrolled. You’ll need to sign up yourself during your Initial Enrollment Period, which starts three months before the month you turn 65 and ends three months after the month you turn 65. That gives you a total of seven months. There are no penalties for signing up at any point during this window, but when your coverage starts depends on which month you enroll.
When Coverage Starts Based on Sign-Up Timing
If you enroll during the three months before your birthday month, coverage begins on the first day of your birthday month. If you sign up during your birthday month itself, coverage starts the following month. Enrolling in the one to three months after your birthday month pushes your start date back further, sometimes by two or three months. The earliest possible coverage comes from enrolling as soon as the window opens.
How to Sign Up Online, by Phone, or In Person
The fastest way to enroll is online through the Social Security Administration at ssa.gov. You can apply for Part A and Part B together, or Part A only. The application asks for basic personal information, your Social Security number, where you were born, and details about any current or past group health plans you’ve had, including start and end dates. If you’re signing up for Part B only (because you already have Part A), you’ll also need your Medicare number and a valid email address.
If you’d rather not apply online, you can call Social Security at 1-800-772-1213, Monday through Friday between 8:00 a.m. and 7:00 p.m. local time. TTY users can call 1-800-325-0778. You can also visit your local Social Security office in person. Use the office locator on ssa.gov to find the nearest location and its phone number.
Deciding on Part A and Part B
Part A covers hospital stays, skilled nursing care, and hospice. Most people pay no monthly premium for Part A because they or a spouse paid Medicare taxes for at least 10 years (40 quarters) while working. There’s very little reason to delay Part A enrollment if you’re 65.
Part B covers doctor visits, outpatient care, preventive services, and medical equipment. The standard monthly premium for Part B is $185 in 2025 and rises to $202.90 in 2026. There’s also an annual deductible of $257 in 2025, increasing to $283 in 2026. You pay Part B premiums for as long as you have the coverage, typically deducted from your Social Security check.
If your income is higher, you’ll pay more. The government adds a surcharge based on your tax return from two years prior. For 2026, the surcharge kicks in at $109,000 for single filers and $218,000 for married couples filing jointly. The higher your income, the larger the surcharge, with the highest bracket starting at $500,000 for single filers and $750,000 for joint filers.
When You Can Delay Part B Without Penalty
If you’re still working at 65 and have health coverage through your employer (or your spouse’s employer), you can typically delay Part B without penalty. The key requirement is that the employer plan must be based on current employment, not retiree coverage or COBRA. Once that job-based coverage ends, you’ll get a Special Enrollment Period of eight months to sign up for Part B.
This is important because if you delay Part B without qualifying employer coverage, you’ll face a permanent late enrollment penalty. The penalty adds 10% to your Part B premium for every full 12-month period you were eligible but didn’t enroll. So if you waited two years without qualifying coverage, your premiums would be 20% higher for the rest of the time you have Medicare. That surcharge never goes away.
Adding Drug Coverage and Medicare Advantage
Original Medicare (Parts A and B) does not cover prescription drugs. You have two main options for additional coverage, and both use the same seven-month Initial Enrollment Period.
A standalone Part D drug plan pairs with Original Medicare. You pick a plan from a private insurer, pay a separate monthly premium, and get prescription coverage. If you delay Part D enrollment without other creditable drug coverage (such as through an employer), you’ll face a penalty of 1% of the national base premium for every month you went without coverage. Over time, that adds up significantly.
A Medicare Advantage plan (Part C) is the other route. These are private plans that bundle Part A, Part B, and usually Part D into one plan. They often include extras like dental, vision, and hearing coverage. To join a Medicare Advantage plan, you must already have both Part A and Part B. Your Initial Enrollment Period for choosing an Advantage plan matches the same seven-month window around your 65th birthday.
If you join a Medicare Advantage plan during your Initial Enrollment Period and change your mind, you can switch to a different Advantage plan or return to Original Medicare within the first three months of having both Part A and Part B.
A Simple Timeline for Turning 65
- Three months before your birthday month: Your enrollment window opens. This is the ideal time to sign up if you need to enroll manually. If you’re auto-enrolled, review your Medicare card when it arrives.
- Your birthday month: You’re in the middle of the window. Coverage for sign-ups this month starts the next month.
- One to three months after your birthday month: Still within the window, but coverage start dates get pushed back. Don’t let the deadline pass without acting.
- Before the window closes: Choose a Part D drug plan or Medicare Advantage plan if you want additional coverage. These use the same seven-month period.
Missing the Initial Enrollment Period doesn’t lock you out forever, but it forces you to wait for the General Enrollment Period (January 1 through March 31 each year), with coverage not starting until July. And you’ll carry the late enrollment penalty on your premiums going forward. For most people turning 65, signing up in the three months before your birthday month is the simplest path to uninterrupted coverage at standard cost.