Start by gathering your Explanation of Benefits (EOB)—a statement from your insurance company showing how they processed your medical claim—and your provider's bill. To match them, compare the patient name, dates of service, provider name, CPT/ICD-10 service codes, billed amounts, and the "allowed amount" between both documents line-by-line, according to the Centers for Medicare & Medicaid Services.
An EOB is not an invoice you must pay in full. It shows you what your insurer negotiated with the provider and what portion you actually owe. The match reveals billing errors, unexpected balances, and whether you're being asked to pay for something your insurance already covered.
Table of Contents
- Decode the key numbers on both documents
- Check your provider's bill against the EOB
- Spot and dispute overbilling
- Appeal if your insurer denied coverage
- Keep records and follow up in writing
- Frequently Asked Questions
Decode the key numbers on both documents
Your EOB lists the provider's original charge, the "allowed amount" (the negotiated rate your insurer accepts), what the insurer paid, and your patient responsibility. Your provider's bill often lists only the original charge, which creates confusion. The critical fact: the "allowed amount" is typically lower than the provider's full charge; for in-network care, the difference is written off and you don't pay it.
Your responsibility equals only what the EOB marks as "patient responsibility," not the provider's starting price. Example: A provider bills $2,000 for an MRI. Your insurer's allowed amount is $800. You owe your deductible or copay (say, $100), not $2,000 or $800. The $700 gap is the provider's negotiated discount.
Check your provider's bill against the EOB
Line up each service on both documents. Confirm the patient name, date of service, and procedure code match. Look for charges on the provider's bill that don't appear on your EOB—these may be bundled charges, unbillable services, or billing errors. If a provider's bill exceeds the EOB's patient responsibility amount, contact the provider's billing department immediately. They may have incorrectly billed you for amounts the insurance company should have covered or applied contractual adjustments unevenly across services.
Spot and dispute overbilling
If you received a Good Faith Estimate (GFE) before the procedure and your final bill exceeds it by $400 or more, you have a formal option. You can file a Patient-Provider Dispute Resolution through CMS within 120 days, with a $25 filing fee. This process is separate from disputing with your insurer.
For uninsured or self-pay care, the GFE is your protection. For insured care, use it as a reference to verify your insurer's allowed amount aligns with what the provider promised.
Appeal if your insurer denied coverage
You have 180 days from receiving a claim denial to appeal it; insurers must decide pre-service appeals in 30 days and post-service appeals in 60 days. Request an internal review first, which your insurer must handle separately from their initial decision. If an insurer denies your internal appeal, you can request an external independent review, which must be decided within 45 days at no cost to you. For Medicare beneficiaries, you have 120 days from the date on your Medicare Summary Notice to appeal, and Medicare Administrative Contractors must decide within 60 days.
Keep records and follow up in writing
Photograph or scan both your EOB and the provider's bill side-by-side for your records. When you contact the provider's billing department, send your dispute or question in writing (email works) and request a written response. This creates a documented trail if the issue escalates. Don't assume a mismatch will resolve itself. Providers don't automatically align their bills to EOBs, and insurers don't monitor every claim for accuracy. The burden is on you to verify before paying.
Frequently Asked Questions
Is the amount on the provider's bill what I have to pay?
No. You owe only the patient responsibility amount listed on your EOB, not the provider's full charge. The difference is a negotiated writeoff for in-network care.
What if the provider's bill doesn't match the EOB?
Contact the provider's billing department immediately in writing. They may have overbilled you or failed to apply the insurance contract rate correctly.
How long do I have to appeal an insurance denial?
You have 180 days from the denial. Your insurer must decide a pre-service appeal in 30 days and a post-service appeal in 60 days.