Around the same number of doctors accept Medicare as those accepting private health insurance. According to research by the Kaiser Family Foundation, approximately 97 percent of non-pediatric primary care doctors accept Medicare. The number accepting private insurance is only one percentage point higher.

However, just because a provider accepts Medicare does not mean they are accepting new Medicare patients. If you're new to Medicare and/or new to that provider, the number drops to around 72 percent.

So, what do you do if your doctor doesn't accept Medicare assignment? And what, exactly, does "accept Medicare" mean?

What Does "Accept Medicare" Mean?

Participating Medicare doctors have signed an agreement that they will work within the guidelines set by the Centers for Medicare and Medicaid Services (CMS). Specifically, this means they agree to:

• Accept the Medicare-approved amount as full payment for covered services, meaning you will never have to pay more than your 20 percent coinsurance
• Submit claims for payment directly to Medicare, billing you for the remainder once Medicare pays its share

All healthcare providers that accept Medicare – including doctors, nurse practitioners, hospitals, clinics, and durable medical equipment providers – agree to these terms. You'll pay less for covered services when you use a Medicare-approved provider, because Medicare negotiates a lower rate than most providers' standard rates. And, of course, you're only responsible for your Medicare Part B coinsurance – not the full amount.

Some Doctors Opt Out of Medicare

Primary care physicians may choose to opt out of the Medicare program for a variety of reasons:

• They don't want to accept the Medicare-approved amount
• Their patient roster may be full
• They find the claims process is too cumbersome

These physicians are known as "non-participating providers."

There are different levels of non-participating. Some providers choose to accept assignment for certain services while others are fully non-participating. If the provider accepts assignment for some types of services, Medicare's limiting charge means they cannot charge you more than 15 percent over the Medicare-approved amount. (This does not apply to fully non-participating doctors.)

The amount a healthcare provider charges above the Medicare-approved cost is called the excess charge.

Very few providers choose to opt out of Medicare completely (less than 1 percent of all physicians). These are known as private contracting physicians.

Your Rights with Non-Participating Providers

Non-participating providers must inform you of which services they accept assignment and when they don't. They may charge you for the entire bill at the time of service – even for Medicare-covered services. But, they should submit a claim for those services to Medicare at no charge to you.

There are instances where you will have to submit a Patient's Request for Medical Payment, using Form CMS-1490S. Medicare will then reimburse you as appropriate.

The excess charge cannot be more than 15 percent higher than the Medicare-approved amount. You are responsible for 100 percent of the excess charge. However, Medigap Plan G and Medigap Plan F cover the excess charge.

What Happens with Private Contracting Physicians?

Thanks to the Balanced Budget Act of 1997, Medicare beneficiaries and doctors are allowed to contract outside of the Medicare program.

Physicians who fully opt out of Medicare may not submit claims for 2 years. If the reason they do not participate is because they've been excluded from the Medicare program, the provider must tell you.

While the doctor must sign an affidavit that they fully opt out of Medicare, you do not have to sign a private contract if you prefer to change to a provider who accepts Medicare. However, if you decide to remain with your opt-out provider, you will enter into a private contract that defines payment terms.

Medicare will not pay for any services received by this provider – even if those services are usually covered by Original Medicare. Your Medicare Supplement Insurance plan will also not pay for any care received. If Medicare would normally pay for the service, the provider must inform you.

If you require emergency or urgent care from a fully non-participating provider, they cannot ask you to sign a contract or refuse to treat you. In addition, Medicare must pay for such care.

CMS.gov provides a database of opt-out providers here.

How to Find a Participating Provider If You Have Original Medicare

Medicare.gov makes it easy to find participating providers, including physicians, hospitals, medical suppliers, and nursing homes. Just click here and then enter your location, provider type, and hit Search. You can also add keywords, such as specialty, to get more refined search results. Or, scroll down the page and choose the provider type to get started.

Finding a Provider with Medicare Part C

Medicare Part C, better known as Medicare Advantage, more closely resembles the private insurance plans many beneficiaries had through an employer. And like group health insurance, most Medicare Advantage plans have provider networks. Doctors within your provider network accept Medicare because they accept your Medicare Advantage plan.

If you prefer to see a provider outside your plan's network, you may have to pay the full cost of care. It depends on the type of plan you have. For example, most HMOs won't cover out-of-network care, while most PPOs do, you just have a higher copayment.

Provider networks often change during the year. If your healthcare provider leaves your plan's network, you either need to choose a new provider or a new Medicare plan.

If you don't qualify for a Special Enrollment Period (SEP), you'll have to wait for specific enrollment periods to change plans.

• The Annual Enrollment Period (AEP) occurs every year from October 15 through December 7. During this time, you may join an Advantage plan, change from one plan to another, or return to Original Medicare.
• The Medicare Advantage Open Enrollment Period (OEP) occurs annually from January 1 through March 31. During OEP, you may either switch to a different Medicare Advantage plan or return to Original Medicare.

Our Find a Plan tool makes it easy to compare Medicare Advantage plans. Just enter your zip code to get started.