How Medicare Works with Other Insurance: What You Need to Know

If you're getting close to age 65 — or already have Medicare — you may also have other types of health coverage, like employer insurance, VA benefits, Medi-Cal, or even a retiree plan. Here’s a quick, easy-to-understand guide on how Medicare works with other types of insurance, who pays first, and what you need to do.

Medicare and Employer Insurance

If you or your spouse are still working, and you're covered by an employer group health plan, you can delay Medicare Part B — but only if the employer has 20+ employees.

Who pays first?

If the employer has 20 or more employees: Employer plan pays first, Medicare pays second
If fewer than 20 employees: Medicare pays first

Make sure to enroll in Part A at 65 (it’s usually free). You can delay Part B without penalty only if your employer plan is creditable.

Medicare and VA Benefits

If you're a veteran, you may have VA health care — but it only works inside the VA system.

Who pays first?

VA and Medicare do not coordinate
You must choose which system to use for each service

You should still enroll in Medicare Part B at 65 to avoid penalties and have coverage outside the VA (e.g., emergencies or civilian doctors).

Medicare and Medi-Cal (Dual Eligibility)

If you have both Medicare and Medi-Cal, you're considered “dual eligible.”

Who pays first?

Medicare pays first
Medi-Cal pays your share (like deductibles, coinsurance, and premiums in some cases)

Many dual-eligible clients qualify for special Medicare Advantage plans (D-SNPs) with extra benefits like:

Dental & vision
Transportation
OTC cards
$0 drug coverage

Medicare and Retiree Coverage

Some employers offer retiree health benefits — but they usually act as secondarycoverage once you turn 65.

Who pays first?

Medicare pays first
Retiree plan pays second

You must enroll in Part A and B to keep most retiree coverage active. Check your plan documents — some retiree plans may drop you if you don’t have Medicare.

Medicare and Cost-Sharing Plans (e.g., Christian Healthcare Sharing Ministries)

These are not insurance — they’re sharing programs, and Medicare does not consider them creditable coverage.

What to know:

They do not delay your need to enroll in Medicare
You may face late penalties if you rely on a sharing plan past age 65

If you’re using a cost-sharing plan, you should enroll in Medicare Parts A and B to protect yourself from large medical bills.

Quick Recap: Who Pays First?

Other Coverage TypeWho Pays First?Should You Enroll in Part B?

Large employer (20+)	Employer first	Optional (if creditable)
Small employer (<20)	Medicare first	Yes
VA benefits	Either system (not both)	Yes
Medi-Cal	Medicare first	Yes
Retiree health plan	Medicare first	Yes
Cost-sharing ministry	Not insurance	Yes