Special Situations

Medicare Secondary Payer: Not Your Primary Plan

Name: Medicare Secondary Payer: Not Your Primary Plan
Creator: Barley Billing Team
Published: 2026-03-26

Written by Barley Billing Team, Medicare Billing Experts | Last reviewed March 26, 2026

Does your notice say something like this?

"Medicare payment cannot be made because another payer must pay first"

"This claim has been denied because we have information that another insurer is your primary payer"

"Payment adjusted because this care may be covered by another payer"

If so, you're in the right place. Here's what it means and what to do.

What This Means

Medicare denied your claim because its records show that another health plan should pay first. Under a law called the Medicare Secondary Payer (MSP) Act, Medicare does not pay as your primary insurance when you have certain other coverage.

This denial means Medicare believes you have another health plan — such as employer coverage, retiree coverage, or COBRA — that is responsible for paying your medical bills before Medicare.

Why This Happens

You or your spouse has employer health coverage. If you or your spouse actively works for an employer with 20 or more employees and you are covered by that employer’s health plan, the employer plan pays first. Medicare pays second.
You have COBRA coverage. In most cases, Medicare pays first and COBRA pays second. But Medicare’s records may not reflect this correctly.
You have retiree health benefits. Retiree coverage typically pays after Medicare, but if Medicare’s records are wrong, claims may be denied.
Medicare’s records are outdated. The Benefits Coordination & Recovery Center (BCRC) keeps track of your other insurance. If their information is wrong — for example, if they think you still have employer coverage after you retired — your claims will be denied.
You have End-Stage Renal Disease (ESRD). Special rules apply. During a coordination period of up to 30 months, your employer plan or COBRA may pay first, and Medicare pays second.
You are disabled and covered by a large group health plan. If you are under 65 with a disability and covered by an employer with 100 or more employees, the employer plan pays first.

Should You Appeal?

Appeal outlook: Mixed

The outcome depends on whether Medicare’s records are correct:

If Medicare’s records are wrong — for example, you no longer have employer coverage but Medicare thinks you do — this can usually be fixed by updating your information with the BCRC. You may not even need a formal appeal.
If you do have other primary coverage — the other plan needs to pay first. An appeal of the Medicare denial will not change this. Instead, submit the claim to your other insurer.
If the other insurer denied the claim — you can send proof of that denial to Medicare, and Medicare may then process the claim.

Most of these situations are resolved by correcting records or billing the right insurer, rather than through a formal appeal.

What To Do Next

Check which insurer should pay first. Visit Medicare.gov’s “Who Pays First” page or call 1-800-MEDICARE to confirm your primary payer.
If you have other coverage, submit the claim to that insurer first. Once they pay (or deny), your provider can then submit the claim to Medicare as secondary.
If your other coverage has ended, contact the BCRC at 1-855-798-2627 to update your records. Have proof ready, such as a termination letter from your employer or former insurer.
Ask your provider’s billing office for help. They deal with coordination of benefits issues regularly and can resubmit claims once the correct primary payer is identified.
Contact your SHIP for free help. Your State Health Insurance Assistance Program can help you sort out which insurer should pay first and assist with any paperwork.

Sources

Medicare.gov: Who Pays First — interactive tool to determine your primary payer
CMS: Medicare Secondary Payer Overview — official MSP rules
CMS: How Medicare Works with Other Insurance (PDF) — detailed guide for beneficiaries
Medicare Interactive: Workers’ Compensation and Medicare — additional coordination rules

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Appeal Deadlines — Check Your Notice for Exact Dates

Original Medicare

120 days from the date on your MSN

Medicare Advantage

At least 60 days (check your denial notice for exact deadline)

Not sure which you have? Check the top of your denial notice. If it names a private insurance company (like Humana, UnitedHealthcare, or Aetna), you have Medicare Advantage. If it says "Centers for Medicare & Medicaid Services," you have Original Medicare.

Frequently Asked Questions

How do I know if Medicare is my primary or secondary insurance?

It depends on your situation. If you or your spouse still works for an employer with 20 or more employees and you have that employer's health plan, the employer plan usually pays first. If you are retired or your employer has fewer than 20 employees, Medicare usually pays first. You can check your status at Medicare.gov or call 1-800-MEDICARE.

Does COBRA count as primary insurance over Medicare?

Usually no. In most cases, if you have Medicare and COBRA at the same time, Medicare pays first and COBRA pays second. The main exception is for people with End-Stage Renal Disease (ESRD), where COBRA may pay first during a coordination period of up to 30 months.

What if I dropped my employer coverage but Medicare still thinks I have it?

Contact the Benefits Coordination & Recovery Center (BCRC) at 1-855-798-2627 to update your records. You may also need to provide proof that the employer coverage ended, such as a letter from your former employer or insurance company.

Can my employer force me to use Medicare instead of the company health plan?

No. If your employer has 20 or more employees, they must offer you the same health benefits as younger employees. They cannot require you to drop the employer plan and use Medicare as your primary insurance.

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This information is for educational purposes only and is not legal or medical advice. Always verify with your doctor's office and insurance company.