What is the difference between primary and secondary coverage?

When you have Medicare and another type of insurance, Medicare will pay primary or secondary for your medical costs. Primary insurance pays first for your medical bills. Secondary insurance pays after. Usually, secondary insurance pays some or all of the costs left after your primary insurance pays (for example, deductibles and copays).

Download this handout for a full breakdown of insurance types, conditions, and who is responsible for primary and secondary coverage.

How does Medicare work with job-based insurance?

•  If your job-based insurance is primary, you may wish to delay Medicare enrollment because you already have primary coverage and can sign up for Medicare Part B later.
• If your job-based insurance is secondary, you should enroll in Medicare Part B to avoid high costs for your care. If Medicare is supposed to be your primary coverage, your job-based coverage may provide little or no coverage if you’re not enrolled in Part B.

Note: Job-based insurance here means insurance from current employment—not coverage for retirees, or former employees.

Enrolling in Medicare after you’ve delayed: You can use the Part B Special Enrollment Period (SEP) to enroll in Medicare later if you’ve been continuously covered by insurance from current work (not retiree) or by Medicare Part B since becoming eligible for Medicare. You can use the SEP while you have that job-based insurance from current work, or in the eight months after losing that insurance. You will need evidence from your employer(s) of your continuous coverage.

How does Medicare work with retiree insurance and COBRA coverage?

• Retiree insurance is health coverage an employer may provide to former employees. Retiree coverage is almost always secondary to Medicare. This means you need to enroll in Medicare to be fully covered.
• If you have COBRA coverage when you become Medicare-eligible, COBRA usually ends the date you get Medicare. You should enroll in Part B right away. If you have Part A or Part B when you become eligible for COBRA, you must still be allowed to enroll in COBRA – and you should enroll in or keep Part B. Medicare is primary insurance, and COBRA is secondary insurance.
• Retiree insurance and COBRA do not entitle you to an SEP to enroll in Part B. You may have to wait for coverage and pay a penalty.

Don’t forget prescription drug coverage! Some employers offer creditable drug coverage for current or former employees. Ask your employer if yours is considered creditable (as good as Medicare Part D). If so, you can delay enrolling in Medicare Part D without a late enrollment penalty if you enroll in Part D later. If your prescription drug coverage isn’t creditable or if you don’t have prescription drug coverage, you should enroll in Part D as soon as possible.

Watch out for people trying to steal your medical identity!

Medical identity theft can happen when someone steals or talks you into giving them your personal information, such as your name and Medicare number, to get medical treatment or products and bills your insurance for it. It is important to protect your Medicare number and only share it with trusted individuals because it can affect your medical, health, or financial records.

Prevent potential medical identity theft by:   

• Never giving out your Medicare number, or other personal information, to anyone other than your doctor, health care provider, or other trusted representatives  
• Always protecting your Medicare number and card as you would a credit card  
• Never giving out your Medicare number to anyone who contacts you through unsolicited calls, texts, or emails  
• Always being cautious of anyone who offers you “free” testing, treatments, medical supplies, or gifts

Report potential medical identify theft if:  

• You gave out your Medicare number over the phone or internet to someone offering medical items like durable medical equipment, genetic/dementia testing, cancer screenings, or back braces
• You gave out your Medicare number over the phone to someone that said you need a ‘NEW’ Medicare card that is plastic, has a chip in it, or is laminated. Medicare is not changing or updating Medicare cards
• You see charges on your Medicare statements for services or items you did not receive or need  
• You are contacted by a debt collection agency for a bill for services you did not receive 
• You receive boxes of braces, testing kits, or other medical supplies in the mail that you did not request or need

Who to contact for help:

• Speak with your employer if you have questions about your employer coverage and how it works with Medicare.
• Enroll in Medicare through the Social Security Administration (SSA) when you’re ready to enroll.
• Call your State Health Insurance Assistance Program (SHIP) for more help or one-on-one Medicare counseling, toll-free 866-413-5337 or email shineinfo@aaaswfl.org. 

The Medicare Rights Center is the author of portions of the content in these materials but is not responsible for any content not authored by the Medicare Rights Center. This document is supported by the Administration for Community Living (ACL), U.S. Department of Health and Human Services (HHS) as part of a financial assistance award totaling $2,534,081 with 100 percent funding by ACL/HHS. The contents are those of the author(s) and do not necessarily represent the official views of, nor an endorsement, by ACL/HHS, or the U.S. government.

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