How to Dispute a Health Insurance Bill

You got a bill. Something looks off. Before you pay it, compare the bill against your EOB and scan for these eight errors — each one can cost you hundreds of dollars if you don’t catch it.

Rule: Never pay a medical bill until you have compared it line-by-line to your EOB. Do not let an unpaid disputed bill go to collections — contact the provider in writing while the dispute is active.

How Common Are Medical Billing Errors?

Studies consistently find that medical billing errors occur in a significant percentage of claims. The most cited figure is that 80% of medical bills contain at least one error, though the frequency of errors that meaningfully affect what patients pay is lower. Regardless, billing errors are common enough that reviewing every bill before paying is worth the time investment, particularly for hospitalizations, surgeries, and high-cost procedures.

The Most Common Medical Billing Errors

• Duplicate charges: The same service billed twice, either from the same provider or from two separate providers (a facility and the attending physician both billing for the same service).
• Incorrect procedure codes (CPT codes): The provider used the wrong CPT code, either billing for a more expensive service than was provided (upcoding) or a different service entirely.
• Incorrect diagnosis codes (ICD-10): A wrong diagnosis code can cause a covered service to appear uncovered, or trigger a denial based on the wrong clinical criteria.
• In-network provider billed as out-of-network: You confirmed the provider was in-network, but the claim was processed at out-of-network rates due to a credentialing issue or billing department error.
• Unbundling: Procedures that should be billed together as a package are billed separately at higher total cost.
• Balance billing from in-network providers: In-network providers cannot bill you for amounts beyond your plan's allowed amount. Receiving a bill above what the EOB says you owe is often improper.
• Surprise billing from out-of-network providers at in-network facilities: The No Surprises Act (effective 2022) protects patients from unexpected bills when they receive care at in-network facilities from out-of-network providers who are not their chosen providers. If you receive such a bill, it may be illegal.
• Preventive care billed with cost-sharing: Covered preventive services must be provided at no cost. A bill for your annual physical, a routine colonoscopy (not diagnostic), or a covered vaccine may be an error.
• Incorrect patient or insurance information: Wrong member ID, date of birth, or insurer information can cause a claim to be rejected or paid incorrectly.

Step-by-Step: How to Dispute a Medical Bill

1. Do not pay immediately. Wait until you receive both the provider bill and the EOB from your insurer. Compare them carefully before paying anything.
2. Request an itemized bill. Ask the provider's billing department for a line-by-line itemized statement listing every charge, the CPT code used, and the date of service. Compare this to your EOB.
3. Compare the itemized bill to your EOB. Every service on the provider's bill should appear on the EOB. Look for discrepancies in amounts, services, and dates.
4. Identify specific errors. Note any duplicate charges, services you did not receive, or amounts that differ from what the EOB shows as your responsibility.
5. Contact the provider's billing department first. Many errors are coding mistakes that the billing department can correct directly with a revised claim submission to the insurer. This is the fastest path to resolution.
6. Contact your insurer if the error is on their side. If the error is in how the claim was processed (e.g., in-network provider processed as out-of-network), call your insurer's member services and ask them to reprocess the claim correctly.
7. File a formal dispute if not resolved. Both providers and insurers have formal dispute processes. Get any dispute in writing, send communications by certified mail, and keep copies of everything.
8. File a No Surprises Act complaint if balance-billed unexpectedly. If you were balance-billed from an out-of-network provider at an in-network facility, file a complaint at CMS.gov or with your state insurance department.

When to Escalate

If the provider and insurer cannot resolve a billing dispute and the amount is significant, consider:

• Your state insurance commissioner: Handles complaints about insurer billing practices
• Your state attorney general: Consumer protection offices handle healthcare billing complaints in many states
• A patient advocate or medical billing advocate: Professionals who specialize in disputing medical bills, often working on contingency

Never let a disputed bill go to collections before exhausting the dispute process. Once sent to collections, resolving the dispute becomes much harder. Need help understanding your EOB or disputing a bill? Call (713) 575-9904.