TL;DR: Medical bills frequently contain errors, and most favor the provider. You can catch the majority yourself: request an itemized bill under your HIPAA right of access, match every line against your insurer's Explanation of Benefits, and check for a few common patterns (duplicate charges, upcoding, unbundling, balance billing, and services you never received). This guide gives you the checks, the 2026 rules, call scripts, and escalation contacts, and shows where Slothwise can do the matching for you automatically.

How common are medical billing errors?

No single audited figure exists, so use two anchors. Consumer billing advocates estimate up to 80% of bills contain errors (Medical Billing Advocates of America, via Becker's Hospital Review), though that reflects bills already flagged for review. The hardest government benchmark is Medicare's Comprehensive Error Rate Testing (CERT) program, which found a 7.66% improper-payment rate ($31.7 billion) in FY2024. CMS notes this is not a fraud rate, so treat it as a conservative floor, not the true consumer error rate.

What are the most common medical billing errors?

A handful of patterns cause most overcharges:

• Duplicate charges: the same service, test, or supply billed twice on one date.

• Upcoding: a higher-paying code than your documentation supports, such as a routine visit billed as a complex one.

• Unbundling: services that should be billed together under one code, split into separately priced codes. CMS's National Correct Coding Initiative (NCCI) defines which pairs should not be billed separately.

• Services never rendered: a charge for a test, drug, or procedure that never happened.

• Incorrect quantities: more units of a drug or supply than were used.

• Balance billing: an out-of-network provider billing you for the gap between their charge and the plan's payment (restricted by the No Surprises Act, below).

How do I get an itemized medical bill?

Request it in writing under your HIPAA right of access (45 CFR 164.524), which entitles you to your billing records and requires the provider to respond within 30 days. The summary bill most hospitals send shows only department totals and hides the line-level charges where errors live. Ask specifically for the itemized statement with CPT and HCPCS codes. Providers may charge a reasonable, cost-based copying fee, but be wary of any quote in the hundreds of dollars.

How do I read my EOB and find the "patient responsibility" line?

Your Explanation of Benefits (EOB) is not a bill; it shows what the provider charged, what your plan allowed, what insurance paid, and your "patient responsibility." Amounts marked as a contractual obligation (CO) cannot be billed to you. Wait for the provider's actual bill, then reconcile it against the EOB's patient-responsibility figure. If the provider bills more than that figure, the gap is often a billing error or improper balance billing.

What is the No Surprises Act and what does it protect in 2026?

The federal No Surprises Act (effective January 1, 2022) bars balance billing for emergency care, for out-of-network providers at in-network facilities (anesthesiologists, radiologists, pathologists, assistant surgeons), and for out-of-network air ambulance. These patient protections remain fully in effect in 2026, with civil penalties up to $10,000 per violation. Important gap: ground ambulance is not covered federally, so those surprise bills can still occur unless your state protects them.

What is a Good Faith Estimate and how does the $400 dispute rule work?

If you are uninsured or self-pay, the No Surprises Act entitles you to a written Good Faith Estimate before scheduled care. If your final bill from a single provider is at least $400 more than that estimate, you can use the federal Patient-Provider Dispute Resolution (PPDR) process. It costs a $25 non-refundable fee, you must file within 120 days of the bill date, and while the dispute is pending the amount cannot be sent to collections and late fees are paused. Keep every estimate you are given.

Are preventive services still free in 2026?

Yes. In Kennedy v. Braidwood Management (decided June 27, 2025), the Supreme Court upheld the structure behind the Affordable Care Act rule requiring most private plans to cover USPSTF "A" and "B" rated preventive services (many cancer and diabetes screenings, PrEP, and more) with no cost-sharing in network. About 150 million Americans rely on this. One caveat: the Court left room for the HHS Secretary to alter recommendations administratively, so watch for future changes. If a routine screening was charged to you, ask whether it was miscoded as a diagnostic visit.

How do I dispute a medical bill, step by step?

Work the process in order and keep everything in writing:

1. Request the itemized bill (HIPAA right of access; 30-day response).

2. Get your EOB from your insurer and place it beside the itemized bill.

3. Match every line and flag the error type (duplicate, upcoding, unbundling, service not received, balance billing).

4. Call the billing department with the specific line and code, and ask for a corrected bill (script below).

5. Dispute in writing and keep confirmation. Use a formal channel: a No Surprises Act PPDR, or your insurer's appeal.

6. Escalate if unresolved (contacts below).

7. Apply for charity care if the bill is unaffordable, even retroactively.

What should I say when I call the billing department?

Keep it specific and calm. Two scripts:

To request records: "I'm exercising my HIPAA right of access under 45 CFR 164.524. Please send me a fully itemized statement with all CPT and HCPCS codes for my visit on [date]. I understand you have 30 days to respond."

To dispute a charge: "On my itemized bill, line [X], code [code], appears to be [a duplicate of line Y / a service I did not receive / upcoded from the visit I actually had]. Please review this line and send me a corrected bill. I'm documenting this call and will follow up in writing."

How do I appeal an insurance denial?

Under the Affordable Care Act, your plan must offer an internal appeal and an independent external review. Appeals are underused but often succeed. A 2023 KFF analysis of ACA marketplace plans found consumers appealed only about 1% of in-network denials, yet 44% of those were overturned. In Medicare Advantage, KFF found that in 2024 only about 12% of denied prior-authorization requests were appealed, but 80.7% of those appeals were overturned in the patient's favor. The lesson: always appeal.

Can medical debt still hurt my credit in 2026?

Yes, for now. A federal rule to ban medical debt from credit reports was finalized on January 7, 2025, then vacated by a federal court on July 11, 2025 (Cornerstone Credit Union League v. CFPB). As of mid-2026, medical debt can again legally appear on credit reports. However, the three major bureaus' voluntary changes still stand: paid medical collections are removed, unpaid medical collections under $500 are not reported, and there is a one-year grace period before medical debt can appear. Some states add further protections.

What if I cannot afford the bill?

Ask for charity care. Nonprofit hospitals (about 60% of U.S. hospitals) must keep a written Financial Assistance Policy under IRS Section 501(r). Many provide free care at or below 200% of the Federal Poverty Level and sliding-scale discounts up to 300 to 400%, and you can often apply retroactively, even after a bill goes to collections. Ask the hospital's billing office for its Financial Assistance Policy and application by name.

Who do I escalate to?

If the provider or insurer will not fix a clear error, escalate:

• Federal No Surprises Help Desk: 1-800-985-3059 (weekdays 8am to 8pm ET, weekends 10am to 6pm ET) to file a complaint about a surprise bill.

• CMS complaints online: cms.gov/medical-bill-rights.

• Your state insurance commissioner for fully-insured plan and appeal issues.

• Your state attorney general's consumer-protection or healthcare division for hospital billing and charity-care disputes.

• HHS Office for Civil Rights if a provider refuses to produce your records within 30 days.

How can Slothwise help you catch billing errors?

Reviewing a bill by hand is slow, and spotting these problems takes knowing how medical coding works. Slothwise does the checking for you. Connect your records, and it reviews your bills and insurance statements and points out anything that looks wrong: a charge you do not recognize, something billed twice, a routine visit coded as a complex one, or a surprise out-of-network charge. It explains in plain language what looks off and why, so you know exactly what to question before you pay. You can do it in the app or right from your text messages, and it is free to start, with no credit card. Slothwise is one option, not the only one: you can also work through the steps above yourself, and for a complicated dispute a human billing advocate or a patient-rights attorney may be worth it.

Frequently asked questions

Is an EOB a bill? No. An EOB from your insurer shows what you owe; the bill comes from the provider. Reconcile the two before paying.

How long do I have to dispute? A No Surprises Act PPDR must be filed within 120 days of the bill date. Insurance appeal deadlines vary by plan, so check your denial letter.

Should I pay while disputing? Use a formal channel. During a PPDR or an insurance appeal the amount cannot go to collections and late fees are paused, but do not simply ignore a bill outside a recognized dispute.

Last updated: July 2026. This article is general information, not legal, financial, or medical advice. For a specific bill, contact your provider, your insurer, the No Surprises Help Desk (1-800-985-3059), or a qualified professional.