When Diane opened a bill from her cardiologist for more than $400, she knew something wasn’t right.

A week earlier, the Medicare Advantage recipient had undergone an electrocardiogram with a cardiologist who was new to her. Before the appointment, she had called her insurance company to confirm her copay. The amount she was quoted was hundreds of dollars less than the $400 bill now sitting in front of her.

So Diane called the provider’s billing office.

At first, the billing department told her the bill was correct. But Diane wasn’t satisfied. She pulled out her insurance card and asked the billing agent to read back the plan ID number listed on the claim.

That’s when they found the problem: The provider had mistaken an “I” in her plan ID number for an “L,” resulting in an inaccurate bill.

The billing agent apologized, corrected the information and resubmitted the claim to Diane’s insurance company. About 30 days later, Diane received an updated statement with the correct copay, which she paid.

Diane’s story had a happy ending, but it’s just one example of a Medicare billing scenario that can cause confusion. Before paying a bill that doesn’t look right, take time to understand what happened. Here are some similar situations:

“I thought this was covered”

Original Medicare (Parts A and B) doesn’t cover everything. Beneficiaries are typically responsible for deductibles, coinsurance (often 20% under Medicare Part B) and services Medicare does not approve.

• Why bills may occur: The service may not be deemed “medically necessary,” or it may fall outside coverage rules.

• What to do: Check your Medicare Summary Notes (MSN), which explains what was billed, what Medicare paid and what you may owe.

Surprise bills with Medicare Advantage Plans

Medicare Advantage plans (Medicare Part C) are offered by private insurance companies. Many have provider networks and specific rules for care.

• Why bills may occur: If you saw an out-of-network provider, skipped a required referral or did not receive prior authorization before a service.

• What to do: Review your plan’s provider network, rules and Evidence of Coverage. Call your plan’s customer service department to ask whether the charge is valid or whether it can be reconsidered. Some Medicare Advantage plans allow members to see out-of-network providers, but the copay or other costs may be higher. To avoid surprises, ask your plan to send you a list of in-network providers or show you where to find the list online before your appointment.

Know when prior authorization is required

Prior authorization means your plan must approve a test, treatment or durable medical equipment (DME) before you receive it.

The basic question your insurance company determines is whether something is “medically necessary.” If they deem that it is, you’re good to go. 

If, however, prior authorization is denied, you, or your requesting provider have the right to appeal the denial by submitting compelling proof that the test, treatment or DME is medically necessary.

Do not assume the provider will always obtain prior authorizations. Many providers know when it is required, but do not always follow through. Call your insurance company before the appointment to confirm what is needed. Your plan is the source of truth for your coverage.

“Isn’t my Medicare Supplement Plan supposed to cover this?”

Medicare Supplement (Medigap) plans help pay costs that Original Medicare doesn’t—but only after Medicare pays its share.

• Why bills may occur: If Medicare denies a claim, the Medigap plan usually will not pay either because it follows Medicare’s guidelines.

• What to do: In that case, start by finding out why Medicare denied the claim. If the issue is corrected and Medicare approves the claim, your Medigap plan should follow.

Watch for duplicate or incorrect charges

Sometimes, billing errors are just that—errors.

• Why bills may occur: Providers may accidentally bill twice, code a service incorrectly or submit outdated insurance information.

• What to do: Compare the provider’s bill with your Medicare Summary Notice or Explanation of Benefits. If something looks off, call the provider’s billing office and ask for a review.

What to do when a bill doesn’t make sense

When a medical bill gives you pause, take these steps before paying:

• Review the paperwork carefully.

• Match the bill to your Medicare Summary Notice or Explanation of Benefits.

• Call the provider’s billing office or your insurance plan for clarification.

• Ask questions until you understand the charge.

• File an appeal if needed. You have rights!

Always review medical bills before paying them. Trust your gut. If a charge feels wrong, ask about it.

Too many Medicare beneficiaries take a medical bill at face value and pay it without question. Be like Diane: Pick up the phone before picking up your wallet.