Beth Braverman is a full-time freelance journalist covering personal finance, healthcare, and careers. A former reporter for MONEY magazine, her work has appeared in dozens of publications, including CNBC.com, CNNMoney.com, and WebMD.
Updated on September 28th, 2023
Diane Omdahl has been helping people navigate the complexities of Medicare for more than three decades. She is a nationally recognized Medicare expert, a registered nurse, serial entrepreneur, and has served as a technical expert for the Centers for Medicare and Medicaid Services (the organization that runs the Medicare program). She is a frequent speaker on Medicare-related issues. She has been featured in many national publications, including the Washington Post, CBS MoneyWatch, Forbes, The Wall Street Journal Market Watch, Kiplinger, and many more. Her most recent startup, 65 Incorporated, helps people 65 and older get the clear, correct, complete, and credible information they need to make important Medicare decisions. She is also the architect behind the i65 Medicare optimization software suite. i65 enables financial advisors to help clients make smart Medicare decisions.
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While Original Medicare is the only insurance for some beneficiaries, it’s also common to have Original Medicare along with another type of insurance in order to reduce out-of-pocket costs, like Medicare Supplement or another federal program. When that happens, there’s a predetermined coordination of benefits, in which Original Medicare is the “primary insurance” and a supplemental plan is the “secondary insurance.” The primary insurance pays first, and the secondary insurance may then make additional payments before the policyholder owes money. That might include some portion of your deductibles or copayments, but it may not.
If you don’t have any other insurance, Orignal Medicare will always be your primary insurance. In most cases, when you have multiple forms of insurance, Original Medicare will still be your primary insurance. Here are several common instances when Original Medicare will be the primary insurer.
If you have job-based insurance from a company with fewer than 20 employees.
Your group insurance plan is the secondary insurer, so you should enroll in Medicare Part B before your group plan will pay its portion of the claim. 1
If you have retiree insurance through a former company.
Some retiree insurance plans do not pay for medical costs if you’re eligible for Original Medicare and don’t enroll. To get the details of how Original Medicare will work with your retirement health benefits, get a copy of your plan’s benefit materials. 2
If you have COBRA insurance after leaving a company where you had health insurance.
You may decide to keep only Original Medicare, and not pay for additional coverage through COBRA.
If you have a disability.
If you’re younger than 65, and your employer-based health plan has fewer than 100 employees, Medicare will pay first. 3
If you have amyotrophic lateral sclerosis (ALS) or end-stage renal disease (ESRD).
Even if you have a group health plan, Original Medicare is the primary insurer as long as you’ve been eligible for Medicare for 24 months or more. 4
If you have TRICARE.
If you are on inactive duty, Original Medicare is the primary insurer, but TRICARE will pay the bills if you get services from a military hospital or other federal health care provider. 5
If you have Medicaid.
Medicaid is always the secondary insurance if you have Medicare. 6
When is Medicare Secondary Insurance
While Original Medicare usually is the primary insurance, there are some instances when a supplement to Medicare is secondary. Two common instances are:
If you have job-based insurance from an employer with 20 or more employees.
This is the case whether you get insurance through your company or your spouse’s employer. Employers must offer workers age 65 or older the same health benefits that they offer to the rest of employees. 7
If you receive workers’ compensation.
Your workers’ compensation insurance will be primary for any services or items related to your workers’ compensation claim. Orignal Medicare will serve as your primary service for all covered medical expenses unrelated to that claim. 8
| You have Original Medicare and… | Primary Insurance | Secondary Insurance |
| …Medicaid | Original Medicare | Medicaid |
| … You are 65 or older and have a group health plan through an employer with 20 or more employees | Group health plan | Original Medicare |
| … You are 65 or older and have a group health plan through an employer with fewer than 20 employees | Original Medicare | Group health plan |
| … You and a retiree health plan through a former employer after you retire | Original Medicare | Retiree coverage |
| … You are disabled and have a group health plan through an employer with 100 or more employees | Group health plan | Original Medicare |
| … You are disabled and have a group health plan through an employer with fewer than 100 employees | Original Medicare | Group health plan |
| … You have veteran’s benefits | Original Medicare pays for Medicare-covered services |
Source: “Your Guide to Who Pays First. .” Medicare.gov. Accessed September 13, 2023.
If you have health insurance through your or your spouse’s employer, and that employer has more than 20 employees, you may be able to delay enrolling in Original Medicare without paying a penalty. In that case, even if you did enroll in Original Medicare at age 65, it would be a secondary insurance and only kick in after your primary insurance paid its share of your claims. To avoid penalties after you (or your spouse) leave your job, you’ll need to enroll in Original Medicare within eight months. 9
If your employer has fewer than 20 employees, Original Medicare would be your primary insurance, and you should enroll during your Initial Enrollment Period. If you miss this chance to enroll in Medicare Part B, you may face a late enrollment penalty. Every year that you delay enrollment in Medicare Part B, your premiums will go up 10% unless you or your spouse have insurance through work. 10
While having multiple forms of health insurance is a fortunate situation, it can also be confusing to determine which one is your primary and which is your secondary–or whether it makes sense to continue paying for both policies. Figuring out which insurance is your primary, however, will make it easier for you to manage your insurance going forward.
1. U.S. Government Website for Medicare. “How Medicare works with other insurance.” medicare.gov (accessed March 28, 2020).
2. U.S. Government Website for Medicare. “Your Guide to Who Pays First” medicare.gov (accessed May 28, 2020)