What to Know About Using Medicare with Secondary Insurance

Medicare does a solid job covering a range of healthcare needs. However, it doesn’t cover everything.

That’s where secondary insurance can help.

Whether it’s a Medigap plan, retiree coverage, Medicaid, or employer-sponsored insurance, having a second payer alongside Medicare can significantly reduce your out-of-pocket costs.

Still, using Medicare with secondary insurance isn’t always straightforward. But understanding how the two work together can help you avoid billing surprises and get the most out of your coverage.

What is Secondary Insurance?

Secondary insurance is exactly what it sounds like: a health plan that pays after Medicare.

When you receive care, Medicare acts as the primary payer, which means Medicare pays first.

Then, your secondary insurance may cover some or all of the remaining costs, including copayments, coinsurance, or deductibles.

Types of Secondary Insurance

People may have secondary insurance from a private insurer, an old employer, or other sources.

Common types of secondary insurance include:

• Medigap (Medicare Supplement Insurance)
• Employer or retiree health plans
• Medicaid (for those who qualify)
• TRICARE or VA benefits

Each type of secondary health insurance works a bit differently, but the goal is the same: to reduce the overall amount you pay out of pocket.

Who Pays First?

The most important concept to understand is the coordination of benefits, or which insurer pays first.

If you have Medicare and a secondary plan, Medicare usually pays first, and your secondary insurance pays second.

However, there are exceptions, including:

• If you’re still working and have employer coverage through a large employer (20+ employees), your employer plan may pay first (i.e. your employer plan acts as primary coverage).
• If you have Medicaid, it almost always pays last, after Medicare and any other insurance.
• If you have retiree insurance, Medicare is typically your primary coverage.

Because these rules can vary, it’s worth checking with both your primary and secondary insurers, so you know exactly how claims will be handled.

What Costs Does Secondary Insurance Cover?

Secondary insurance can help cover expenses that Medicare leaves behind, including:

• Part A hospital deductibles
• Part B coinsurance (typically 20%)
• Skilled nursing facility coinsurance
• Foreign travel emergency care (in some cases)

Let’s say you have Original Medicare and see a doctor. Medicare Part B generally pays 80% of the approved amount. Without secondary insurance, you’re responsible for the remaining 20%. With the right secondary plan, that 20% could be partially, or even fully, covered.

Medigap vs. Other Secondary Coverage

One of the most popular forms of secondary insurance is Medigap, also known as Medicare Supplement Insurance. Medigap plans are specifically designed to fill “gaps” in Original Medicare coverage.

These plans are standardized and labeled (say, Plan G or Plan N), making it easier to compare benefits. Many Medigap plans cover most out-of-pocket costs, offering predictable expenses and broad provider access.

Other types of secondary insurance, like employer or retiree coverage, aren’t standardized. Some offer strong benefits, while others have varying levels of coverage. Some even include prescription drug coverage, which is something Medigap doesn’t cover.

Can You Have Secondary Insurance with Medicare Advantage?

If you’re enrolled in a Medicare Advantage plan (Part C), you generally can’t use Medigap as secondary insurance.

Medicare Advantage plans are designed to replace Original Medicare and include their own cost structure, provider networks, and coverage rules.

However, you still have other secondary coverage options, including Medicaid or employer-sponsored insurance, that coordinate with your Medicare Advantage plan. Coordination rules vary between plans.

How Claims Work with Primary & Secondary Coverage

What happens when you make a claim while carrying primary and secondary coverage? In many cases, the claims process is relatively smooth.

Providers typically bill Medicare first.

Then, once Medicare pays its share, the claim is automatically sent to your secondary insurer.

However, not all providers handle primary and secondary insurance billing automatically. That’s why it’s a good idea to:

1. Check with the provider to ensure they have both insurers on file.
2. Carry both insurance cards.
3. Review your Medicare Summary Notice (MSN) and secondary insurer statements.

By following these tips, you can catch billing errors early and ensure your secondary insurance coverage is applied correctly.

Final Word: Is Secondary Insurance Worth It?

For many people, secondary insurance is worth it.

Secondary insurance can give you more predictable healthcare costs.

Medicare alone, meanwhile, can leave you exposed to deductibles, coinsurance, and no out-of-pocket maximum under Part A and Part B.

Secondary insurance can reduce or eliminate out-of-pocket costs, expand coverage in certain situations, and provide financial peace of mind.

The downside of secondary insurance, of course, is that it’s not free; you’ll need to weigh monthly premiums against potential savings.

Overall, using Medicare with secondary insurance can make coverage more complete. However, it’s important to review options carefully to find the best combination that works for your budget, health needs, and peace of mind.