How Medicare Claims Work: What Adult Children Need to Know

Most adult children helping a parent with Medicare focus on plan selection — and for good reason. But once enrollment is done, a different set of problems emerges: claims are denied, bills arrive that should have been covered, explanation-of-benefits documents pile up unread, and nobody is quite sure whether the right amount was actually paid.

Understanding how Medicare claims work is not just useful trivia. It is the mechanism through which you catch errors, fight improper denials, and make sure your parent's benefits are actually being delivered.

How Claims Get Filed

In most cases, your parent never files a Medicare claim themselves. The billing process is supposed to be automatic.

With Original Medicare, the doctor, hospital, or other provider submits the claim directly to Medicare on your parent's behalf. This is called "accepting assignment" — when a provider accepts Medicare assignment, they agree to bill Medicare directly and accept the Medicare-approved amount as full payment. They cannot charge more than that approved amount (except for a small category of non-participating providers who can charge up to 15% above the approved rate, known as excess charges).

Providers are required to file Medicare claims within one year of the date of service. If a provider tells your parent they need to file the claim themselves, that is a red flag — legitimate Medicare providers handle the billing.

With Medicare Advantage, claims flow through the private insurer rather than directly through Medicare. Your parent's providers submit claims to the plan, the plan processes them according to its own coverage rules, and then settles with the provider. This is why Medicare Advantage prior authorization matters so much — a procedure that was not pre-authorized may result in the claim being denied entirely, leaving your parent with a large bill.

Tracking Claims: MyMedicare.gov

The most powerful tool for monitoring your parent's Medicare claims is MyMedicare.gov. This is the official federal portal where all Original Medicare claims are recorded. Here is what you can do there:

• View all claims from the past 36 months
• See what was billed, what Medicare approved, what Medicare paid, and what your parent owes
• Download the full claims history (useful for detecting billing fraud or errors)
• Set up a Medicare Summary Notice preference (more on that below)

To access it, your parent needs to log in using their Medicare number and other identifying information. If you are managing Medicare on your parent's behalf, you need to be established as an authorized representative. Form CMS-1696 (Appointment of Representative) authorizes you to view claims, speak with Medicare on the phone, and file appeals.

Without this form on file, Medicare representatives are legally prohibited from discussing your parent's claims with you — even if your parent is on the line or gives verbal consent.

Understanding the Medicare Summary Notice

Every quarter (or more frequently if there is significant claims activity), Medicare mails your parent a Medicare Summary Notice (MSN). Think of it as the Medicare equivalent of a bank statement.

The MSN shows:

• Services received during the period
• What was billed vs. what Medicare approved
• How much Medicare paid
• What your parent owes (the coinsurance portion)
• Any claims that were denied and the reason

Read every MSN. Medicare billing fraud and simple coding errors are far more common than most families realize. Studies suggest that billing errors affect a significant percentage of Medicare claims — ranging from duplicate charges for the same service to procedures billed at the wrong level of complexity (a common upcoding problem in medical billing).

Your parent can also opt to receive MSNs electronically through MyMedicare.gov if they prefer not to wait for the quarterly mail delivery.

Common Reasons Claims Are Denied

Medicare denies claims for a variety of reasons, and not all denials are correct. The most common reasons include:

Not medically necessary: Medicare determines that the service was not appropriate for the diagnosed condition. This is the most contested denial reason and is frequently overturned on appeal.

Service not covered: Some services genuinely fall outside Medicare's scope (routine dental, most vision care, hearing aids, acupuncture with limited exceptions). These denials are usually correct.

Missing or incorrect information: A billing code error, incorrect patient ID, or missing referral documentation can trigger a denial that is purely administrative — not a real coverage problem.

Duplicate claim: The same service billed more than once. Can be an error by the provider's billing department or, in cases of fraud, deliberate.

Provider not enrolled in Medicare: If your parent saw a provider who does not participate in Medicare, the claim will be denied. Always verify Medicare participation before a major appointment.

Prior authorization not obtained (Medicare Advantage only): This is the most common denial source in Medicare Advantage. The insurer required pre-approval for a procedure that the doctor ordered without getting it first.

How to Appeal a Denied Medicare Claim

A denied claim is not the end of the road. The Medicare appeals process has five levels, and the success rate improves at each level — over 80% of denials that reach an independent review are eventually overturned.

Level 1: Redetermination

File a redetermination request with the contractor that processed the original claim (the name and address appear on the MSN). The deadline is 120 days from the date of the denial notice. You can submit in writing or online via MyMedicare.gov.

Attach any relevant documentation: physician notes explaining medical necessity, prior authorization correspondence, or corrected billing information. The contractor must respond within 60 days.

Level 2: Reconsideration

If the redetermination is denied, the case goes to a Qualified Independent Contractor (QIC). File within 180 days of the redetermination decision. The QIC is not affiliated with the original Medicare contractor — this is the first genuinely independent review. Deadline for response: 60 days.

Level 3: Office of Medicare Hearings and Appeals (OMHA)

If still denied and the amount at stake meets the threshold ($200 in 2026), you can request a hearing before an Administrative Law Judge. File within 60 days of the QIC decision. This level takes longer — the wait can stretch 18–24 months — but ALJ decisions frequently reverse lower-level denials.

Levels 4 and 5: Medicare Appeals Council and Federal Court

For high-value disputes or complex legal questions. Most families resolve their disputes at Level 2 or 3.

Key point: Never accept a denial as final without at least filing a redetermination. The process is designed to be navigable without an attorney, and the success rate justifies the effort.

Medicare Advantage Claims: A Different Process

If your parent is on Medicare Advantage, the claims and appeals process runs through the private insurer rather than directly through Medicare. The general structure is similar — deny, request internal review, escalate to an external independent organization — but the timelines and rules differ.

For Medicare Advantage, the appeals process includes:

1. Internal appeal to the MA plan (file within 60 days of denial)
2. External review by an Independent Review Organization (IRO)
3. OMHA hearing (if dollar threshold met)

A critical difference: Medicare Advantage plans are permitted to require prior authorization for many services. If the plan denies coverage because prior authorization was not obtained, the appeal strategy focuses on whether the authorization denial was appropriate — not just whether the service itself was covered.

If your parent's doctor believes a treatment is medically necessary and the MA plan is stalling or denying, ask the doctor to request a peer-to-peer review — a direct call between the treating physician and the plan's medical director. This step resolves many prior authorization disputes before a formal appeal is needed.

Spotting Medicare Billing Fraud

Billing fraud costs the Medicare program billions of dollars annually — and your parent's Medicare number is the key that makes it possible. Protecting that number is as important as protecting their Social Security number.

Signs that a claim may be fraudulent:

• MSN shows a service your parent never received
• A provider bills for equipment that was never delivered
• A "free" screening offer turns into a billed claim
• Claims from providers your parent has never visited

If you spot suspicious claims, report them to the Office of Inspector General at 1-800-HHS-TIPS (1-800-447-8477) or through oig.hhs.gov. Medicare beneficiaries are protected from liability for fraudulent claims they did not authorize, but the report still needs to be made.

A Practical Monitoring Routine

Set up a simple quarterly routine to stay on top of your parent's Medicare claims:

1. Log into MyMedicare.gov and review all claims from the past 90 days
2. Match claims against your parent's appointment calendar — confirm each claim reflects a real visit
3. Check the "Amount Billed" vs. "Medicare Approved" columns — large gaps may indicate a provider billing above approved rates
4. Review any MSN documents that arrived by mail during the quarter
5. Note any denials and check whether an appeal deadline is approaching

This process takes 20–30 minutes per quarter and catches problems before they become expensive disputes.

Understanding Medicare claims is part of the broader job of managing a parent's healthcare finances. It connects directly to plan selection (Original Medicare claims are more transparent and predictable than Medicare Advantage claims), to cost projections, and to protecting your parent from fraud.

For a comprehensive guide that covers Medicare plan selection, enrollment timing, claims management, and low-income assistance programs all in one place, the Medicare Enrollment Guide provides the structure to manage all of this without starting from scratch each time a new question arises.