Medicare and Social Security

Medicare and Social Security are run by different federal agencies, but they are built to work together once you turn 65. Medicare is the federal health insurance program for people 65 and older, administered by the Centers for Medicare & Medicaid Services (CMS). Social Security is the federal retirement, disability, and survivor benefit program administered by the Social Security Administration (SSA).

If you are already collecting Social Security retirement benefits when you turn 65, Medicare automatically enrolls you in Part A and Part B, and your Part B premium comes straight out of your monthly check. If you have not started Social Security yet, you have to sign up for Medicare on your own and pay your premium directly. Delaying Social Security to grow your retirement benefit does not delay your Medicare enrollment deadline, and missing that deadline can trigger a permanent late enrollment penalty.

Whether Medicare enrolls you automatically depends on your Social Security status, not your age alone.

If you are already receiving Social Security retirement benefits when you turn 65, the Social Security Administration enrolls you in Medicare Part A and Part B without any action on your part. Your Medicare card arrives in the mail about three months before your 65th birthday.

If you are not receiving Social Security at 65, whether because you have not filed for benefits yet or you are still working, you have to enroll in Medicare yourself through the Social Security Administration during your Initial Enrollment Period, the seven-month window centered on your 65th birthday month. For a full breakdown of which enrollment window applies to your situation, see our guide to Medicare special enrollment periods and qualifying events.

Once you are enrolled, how you pay your Part B premium also follows your Social Security status.

If you receive Social Security retirement benefits, Medicare deducts your Part B premium automatically from your monthly check before it is deposited. You do not receive a separate bill.

If you are not yet on Social Security, Medicare bills you directly, usually every three months, or you can set up an electronic funds transfer that pulls your premium from a bank account on a set date each month. Premium amounts change annually and can be higher if your income is above set thresholds. Our guide to real-world Medicare costs breaks down what drives your total premium.

You can wait until age 70 to claim Social Security retirement benefits and earn delayed retirement credits that increase your monthly payment. That delay applies only to Social Security. It does not delay your Medicare enrollment requirement.

You still need to enroll in Medicare during your Initial Enrollment Period at 65, unless you qualify for a Special Enrollment Period because you or a spouse have coverage through current employment. If you enroll late without a qualifying exception, Medicare can apply a late enrollment penalty.

IRMAA stands for Income-Related Monthly Adjustment Amount, a surcharge Medicare adds to your standard Part B and Part D premiums when your modified adjusted gross income is above set thresholds. The threshold and surcharge amounts change every year, as described on the Social Security Administration's page on Medicare premiums for higher-income beneficiaries.

Medicare bases your IRMAA on the tax return you filed two years before the current plan year. If you had a one-time income spike, such as selling a business or a large capital gain, and your income has since dropped, you can ask Social Security to reconsider your IRMAA based on a documented life-changing event.

IRMAA works in the opposite direction from assistance programs for lower-income beneficiaries. If your income is limited rather than elevated, you may qualify for help through a Medicare Savings Program instead of paying a surcharge.