To sign up for Medicare, you need your Social Security number, your birthplace (city, state, and country), and details about any employer health insurance you currently have or had after age 65. Most people can apply online in under 20 minutes once they have this information ready. Depending on your situation, you may also need documentation from your employer or a valid email address.
Basic Personal Information
The Social Security Administration handles Medicare enrollment, and the core information they ask for is straightforward:
- Social Security number
- Place of birth (city, state, and country)
- Health insurance details, including start and end dates for any current or past group health plans, especially any coverage you had after age 65
If you’re signing up for Part B specifically, you’ll also need a valid email address and your existing Medicare number (if you already have Part A). You don’t need to dig up your birth certificate or bring stacks of paperwork for a standard enrollment. Most of the process relies on information Social Security already has on file about you.
If You’re Still Working or Recently Retired
People who delayed Medicare because they had health insurance through a job face an extra step. To qualify for a Special Enrollment Period and avoid late penalties, you need proof that you had group health coverage based on current employment within the last 8 months. This proof comes in the form of a document called CMS-L564, which your employer fills out.
The form requires your employer to confirm several things: the date your coverage began, whether it has ended (and when), and the dates you worked for the company. You’ll need to provide your name, Social Security number, your employer’s name and address, and if the coverage was through a spouse or family member, their name and Social Security number as well. Your employer completes their section, then you submit it along with your enrollment application to your local Social Security office.
This is the single biggest documentation hurdle in the Medicare sign-up process, and it trips people up because it requires coordination with your employer’s HR department. Give yourself a few weeks to get the form completed, especially if you’re working with a large company where paperwork moves slowly.
What You Need to Know About Your Income
Medicare uses your tax return to determine whether you’ll pay more than the standard Part B premium. For 2025, the standard premium is $185 per month, but higher earners pay significantly more. If your modified adjusted gross income is above $106,000 as an individual filer (or $212,000 for joint filers), your monthly premium increases in tiers, topping out at $628.90 per month for individuals earning $500,000 or more.
You won’t need to submit tax documents during enrollment. Medicare pulls this information automatically from the IRS using a prior year’s tax return. But it helps to know where you fall so you aren’t surprised by your premium. If your income has dropped significantly since the tax year they’re using (due to retirement, for example), you can request an adjustment by contacting Social Security.
Requirements for Non-Citizens
If you’re a permanent resident with a green card, you can enroll in Medicare, but you must have lived continuously in the United States for at least five years before applying. You also need to be 65 or older. This five-year residency requirement applies specifically to people who didn’t work long enough in the U.S. to qualify for premium-free Part A. If you or your spouse paid Medicare taxes for roughly 10 years or more, you qualify for Part A at no monthly cost regardless of citizenship status.
When to Have Everything Ready
Your Initial Enrollment Period lasts seven months. It starts three months before the month you turn 65 and ends three months after your birthday month. Signing up during the first three months gets your coverage started sooner, so having your information gathered before that window opens is ideal.
If you miss this window and don’t have qualifying employer coverage, you’ll pay a late enrollment penalty of 10% added to your Part B premium for every full year you could have signed up but didn’t. That penalty sticks with you for as long as you have Part B. Someone who waited two years past their enrollment window, for example, would pay 20% more on every monthly premium going forward.
How to Actually Sign Up
The fastest route is online through the Social Security website. You’ll need to create a “my Social Security” account first, which requires verifying your identity. Once logged in, the application walks you through providing your Social Security number, birthplace, and insurance history.
If you prefer not to apply online, you can contact your local Social Security office in person or call Social Security at 1-800-772-1213 (TTY users: 1-800-325-0778). If you or your spouse worked for a railroad, enrollment goes through the Railroad Retirement Board at 1-877-772-5772 instead.
For people enrolling during a Special Enrollment Period, remember that the CMS-L564 form from your employer and your enrollment application need to be submitted together to your local Social Security office. The online system handles standard enrollments smoothly, but Special Enrollment Period applications with employer documentation are sometimes easier to manage in person or by mail.