How to Spot and Respond to Medicare or Insurance Billing Errors: A Senior’s How-To

Worried your Medicare or insurance bill isn’t right? Start here.

Billing mistakes and fraud can cost seniors thousands—and recent 2025–2026 enforcement actions make that painfully clear. In January 2026 a major settlement put a spotlight on Medicare Advantage billing practices, and state and national regulators have signaled increased oversight. This guide gives you a clear, step-by-step process for spotting errors on Explanation of Benefits (EOB) notices, disputing claims, contacting your state insurance department and the NAIC, and documenting evidence so you protect your money and your rights.

Why this matters in 2026

Large settlements and regulatory changes in late 2025 and early 2026—most notably a record settlement involving a major insurer accused of overstating diagnoses to collect higher Medicare Advantage payments—mean regulators are watching, but patients still bear the burden of catching mistakes. Medicare Advantage enrollment has continued to grow, and more seniors now rely on private plans. While enforcement is stepping up, the frontline defense against billing errors is an informed consumer.

"Medicare Advantage is a vital program that must serve patients’ needs, not corporate profits. Fraud on Medicare costs the public billions annually..." — U.S. Attorney, DOJ announcement (January 2026)

Quick roadmap — What to do now (inverted pyramid)

1. Stop and collect: Keep every EOB, bill, and receipt. Do not ignore a confusing charge.
2. Compare: Match the EOB to your calendar and medical records right away.
3. Ask questions: Call your provider and plan using the scripts below.
4. Document everything: Create a dated log, scan documents, and send dispute letters with tracked mail.
5. Escalate: If unresolved, file a complaint with your state insurance department and the NAIC consumer portal; consider SHIP help and, in some cases, contacting Medicare or state attorney general.

Step 1 — How to review an EOB like a pro

Don’t be intimidated by abbreviations. An Explanation of Benefits (EOB) is a statement from your insurance plan explaining what was billed, what the plan paid, and what you may owe. For Original Medicare you may also receive a Medicare Summary Notice (MSN). Here’s how to review one efficiently:

Checklist for a quick EOB review

• Confirm identity: Are your name, Medicare/ID number, and the provider’s name correct?
• Check dates: Does the service date match the day you received care?
• Service description and codes: Look at the CPT/HCPCS or diagnosis (ICD) codes—do they match what you received?
• Provider billed amount vs. plan paid amount: Is there a duplicate charge or an unexpected balance?
• “Not Covered” or “Denied” reasons: Read any denial reasons carefully—these tell you whether it’s a paperwork issue, medical necessity question, or coding error.
• Copays/coinsurance: Does the amount you owe match your plan’s stated cost-sharing?

Common red flags

• Charges for a service or date you didn’t receive.
• Duplicate entries for the same treatment or test.
• Services you didn’t authorize (e.g., home health visits you never had).
• Upcoding: more expensive procedures than what you recall.
• Unbundling: billing multiple codes separately when they should be billed as one package.

Step 2 — Gather evidence and document everything

Good documentation is your best defense. Start a file (physical and digital) for every billing issue. Here’s what to collect and how to organize it.

What to save

• Original EOB(s) and any paper bills.
• Receipts, copay slips, and Explanation of Benefits you received by mail or online.
• Notes from conversations: date/time, person’s name, phone number, and summary of the call.
• Medical records or physician notes that confirm services, dates, and diagnoses.
• Prescription labels or pharmacy receipts if medications are involved.
• Any emails or letters exchanged with the provider or plan.

How to document

• Create a single timeline listing dates of service, date billed, when you noticed the error, and every contact you made.
• Scan documents into PDF format. Use clear file names like: "2026-01-12_EOB_Hospital.pdf".
• Use a contact log—a simple spreadsheet or notebook with dates, names, and outcomes.
• Send letters by certified mail and keep receipts. For emails, keep a copy in a dedicated folder and request read receipts if possible.

Tip: Under HIPAA, providers must give you access to your medical records—normally within 30 days (with a possible 30-day extension). If a provider delays, note the request date and any responses.

Step 3 — Call, then follow up in writing (sample scripts)

Start with the billing office of the provider who billed you. If the problem is an insurance coding or payment issue, contact the plan. Keep calls short and factual. Use these scripts.

Script for calling the provider billing office

"Hello, my name is [Name]. I received an EOB from [Plan name] showing a charge for [service] on [date]. I did not receive / I believe the code is incorrect / I was not charged at the time. Can you review the claim and confirm what was billed and why? My account number is [number]."

Script for calling your Medicare Advantage plan or insurer

"Hello, I’m calling about claim number [x] on my EOB dated [date]. The EOB lists a charge for [service] that I did not receive / appears duplicated / looks like upcoding. I’d like to open a formal dispute or grievance and get instructions on next steps. Please tell me the deadline to file and any forms I need."

Always ask: "What is the timeline for resolving this? Will I get a written decision?" and request a reference number for the call.

Step 4 — File a formal dispute or appeal

Insurance plans and Medicare have formal dispute and appeal processes. Don’t rely on informal phone promises—get it in writing. Below is a practical approach.

How to prepare a dispute letter

• Include your name, member ID, claim/EOB number, provider name, and date(s) of service.
• State the error in one clear sentence (e.g., "This charge is for services I did not receive on 11/05/2025").
• Attach copies (never send originals) of supporting documents: EOB, receipts, medical notes.
• Request a specific remedy: correction of claim, refund, or removal of balance.
• Sign and date, and send via certified mail or the plan’s secure portal. Keep proof of delivery.

Check your plan documents or EOB for exact appeal deadlines—many allow 60–120 days to file a grievance or appeal. If you miss a deadline, still file: sometimes plans will accept late appeals with a good reason.

For a quick start, you can adapt templates; a short dispute letter template or simple invoice-style summary helps you list claim numbers and requested remedies clearly.

Step 5 — When to contact regulators and consumer help

If your provider or plan does not resolve the problem, or you suspect fraud, escalate to regulators and consumer assistance programs. Recent NAIC leadership announcements in 2026 emphasize the state-based regulatory role—your state insurance department is often the most direct route for consumer complaints.

Who to contact (priority order)

1. State Insurance Department: File a consumer complaint with your state’s department of insurance (also called department of banking & insurance in some states). They handle plan conduct, claims handling, and market conduct investigations.
2. NAIC Consumer Assistance: The National Association of Insurance Commissioners (NAIC) provides consumer resources and complaint guidance—use the NAIC consumer portal to find state contact info and file complaints when your plan is unresponsive.
3. Medicare: For Original Medicare issues, contact 1-800-MEDICARE (1-800-633-4227) or visit Medicare.gov. For Medicare Advantage appeals and grievances, you can file with the plan and escalate to CMS if unresolved.
4. State Health Insurance Assistance Program (SHIP): Free, unbiased counseling to help you navigate appeals and complaints.
5. State Attorney General: For suspected fraud or patterns of deceptive practices, especially if you are a part of many affected enrollees.

How to file a complaint with the state insurance department

• Visit your state department’s website and find the "File a Complaint" section.
• Complete the form—include claim numbers, copies of EOBs, and a timeline of contacts.
• Explain the outcome you want (correction, refund, policy correction).
• Ask for a complaint tracking number and expected time to investigate.

What to expect: Many states will log your complaint and may request additional documents. Regulators sometimes mediate with the insurer or open a market-conduct review for patterns of complaints—especially when national headlines draw attention.

Step 6 — If you suspect wider fraud or systemic issues

The DOJ and whistleblowers have recently prosecuted large-scale Medicare Advantage billing schemes. If you believe billing errors reflect intentional upcoding or false claims, consider:

• Reporting to your state attorney general or the DOJ’s tips portal (for serious, systemic fraud).
• Contacting a trusted consumer advocacy organization or SHIP for next steps.
• Talking to an attorney before pursuing litigation—especially if you are considering joining a whistleblower action (qui tam). This is advanced and not typical for routine disputes.

Practical timelines and expectations (realistic)

• Immediate: Call provider and insurer the day you spot an error. Create a dated log and start your documentation folder.
• Within 7–14 days: Send a written dispute and follow-up call. Ask for a written decision within 30 days.
• 30–90 days: Most plan determinations or corrections happen here. If unresolved, file a regulator complaint and consider SHIP help.
• 90+ days: If the issue involves potential fraud or many affected patients, regulators may open broader investigations—but this can take months.

Real-world examples (brief case studies)

Example A: Duplicate lab charge

Mrs. L. found two identical lab charges on her EOB for the same blood draw. She called the lab billing office, sent the EOB with a short dispute letter, and the lab issued a corrected claim within three weeks. She documented the correspondence and never paid the duplicate charge.

Example B: Suspicious diagnosis coding (systemic)

Mr. R. noticed more severe diagnosis codes on his EOB than the conditions his doctor recorded. After the plan denied his appeal, he filed a complaint with the state insurance department. The complaint contributed to a wider market review announced by the state regulator—an outcome that took months but led to plan corrections for several enrollees.

Protecting yourself while disputes are pending

• Do not ignore collection notices—inform the collector that the charge is disputed and provide copies of your dispute letter and tracking number.
• If a provider pressures you to pay a disputed charge, ask them to place the account on hold while the dispute is resolved and get that confirmation in writing.
• Monitor your credit reports and consider a fraud alert if you see unexpected collection activity; also consider secure local storage and off-line backups (see storage best practices).

Advanced strategies and 2026 trends to watch

Regulators in 2026 are more focused on:

• Medicare Advantage coding practices: Increased audits and larger settlements when systemic upcoding is found.
• Market conduct oversight: State insurance departments, backed by NAIC guidance, are coordinating more closely on complex issues.
• Data-driven complaints: Consumers who document patterns (dates, repeated codes, multiple affected members) are more likely to trigger regulator action; see practical approaches to evidence capture and preservation.

Be proactive: if you spot the same questionable codes or charges across multiple EOBs or among friends in your plan, share your findings with your state regulator and SHIP. Collective documentation often accelerates investigations.

Top practical takeaways

• Act quickly: Most appeals and disputes have firm deadlines—start within days, not months.
• Document everything: A clear timeline and copies of documents make disputes simple to prove.
• Use the right channels: Call first, then file written disputes, and escalate to state insurance departments, NAIC resources, SHIP, or Medicare as needed.
• Be persistent: Many billing errors are resolved by persistence; some systemic problems require regulator action.

Resources and contacts to keep handy

• Medicare: 1-800-MEDICARE (1-800-633-4227) or Medicare.gov for appeals and questions.
• State Insurance Department: Find your state’s consumer complaint form on your state government website (search: "[Your State] department of insurance consumer complaint").
• NAIC: Consumer resources and state contact links via the NAIC consumer portal.
• SHIP: Free local counseling—search "SHIP" with your state to find contact info.

Final note — You are not powerless

Recent enforcement actions in 2025–2026 show regulators are serious about rooting out fraud and abusive billing practices, but they can’t find every bad claim. Your vigilance matters. When you save EOBs, track calls, and use the formal dispute process, you become the first and most effective line of defense for your finances—and often for other seniors in your plan.

Call to action

Start a billing log today: gather your most recent EOBs, scan them, and create a one-page timeline. If you find a suspicious charge, use the sample scripts and checklist above to call your provider and plan. Need help? Contact your local SHIP counselor for free, unbiased assistance, and consider filing a complaint with your state insurance department if the plan won’t correct the error. Stay organized, be persistent, and protect your rights—your health coverage should serve you, not surprise you.

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