Your insurance denies a claim. Or pays less than you expected. Or codes the service as "not medically necessary" when your doctor clearly recommended it. You have rights here—and you have recourse.
This is where the investigation gets serious. Insurance companies make thousands of coverage decisions daily. Some are correct. Some are mistakes. Your job is to gather evidence, build your case, and appeal the decision through the proper channels.
When to dispute with insurance vs. the provider
Here's a crucial distinction: there are two different disputes you might face, and they require different approaches.
Provider billing disputes: The hospital or doctor billed something incorrectly. Wrong code, duplicate charge, service you didn't receive. In this case, you dispute with the provider—the hospital. Request an itemized bill, identify the error, and ask them to correct it.
Insurance disputes: Your insurer made a decision about your claim. They denied it. They underpaid it. They said something is "not covered" or "not medically necessary." In this case, you dispute with your insurance company, not the provider.
This guide focuses on insurance disputes. The most common reasons for claim denial or underpayment:
- Service deemed "not medically necessary"
- Out-of-network provider (and your policy excludes out-of-network care)
- Prior authorization wasn't obtained
- Coding error on the provider's side that insurance caught
- Service falls outside your plan's coverage terms
- Benefit maximum or deductible issues
When you receive a denial, your insurance company (usually via EOB or denial letter) will explain the reason. For a detailed breakdown of what to look for, see our guide on reading your EOB. That explanation is your starting point for appeal, and the process for appeals is our next step.
What to gather before you call
Before you contact your insurance company, get your evidence organized. Insurance companies handle thousands of appeals. Yours will move faster and more persuasively if you come prepared.
Gather these documents:
- The denial letter or EOB. The document from insurance explaining why the claim was denied or paid less than expected. Note the specific reason for denial.
- Your insurance ID card. For reference and to confirm your policy number.
- Doctor's notes. Medical records supporting the medical necessity of the service. Ask your provider to send these to you in writing.
- Prior authorization confirmation. If you did obtain prior auth, include proof. If you're claiming you should have been told about the requirement, note that.
- Plan documents. Your insurance policy or summary of benefits showing what's covered. Insurance companies often include policy summaries with your EOB.
- Any written communication with insurance. Previous calls, emails, or letters mentioning this service or claim.
The more supporting evidence you have, the stronger your appeal. Insurance companies are required to consider new information in appeals. Medical necessity is often the deciding factor—so doctor's notes explaining why the service was clinically necessary can turn a denial around.
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Step 1: File an internal appeal
An internal appeal is your first step. You're asking your insurance company to reconsider their initial decision. By law, they must have a process for this.
The timeline: You have 180 days from the date of denial to file an internal appeal. Don't wait. File as soon as you can.
How to file: Your EOB or denial letter should tell you how to appeal. Usually there's a phone number or mailing address. Some insurers allow online appeals through their member portal. Call and ask: "I'd like to file an internal appeal of this claim denial. What's the fastest way to submit my appeal?"
What to include in your appeal letter: Keep it concise but complete. Here's a template:
"I am appealing the denial of my claim [claim number] dated [date of service]. The original denial reason was [stated reason from EOB]. I respectfully disagree with this decision and am requesting reconsideration.
Supporting evidence: [Briefly state your case—e.g., 'My doctor's notes attached confirm the medical necessity of this service,' or 'The service is covered under my plan per the summary of benefits attached.']
I request that you reverse this denial and process the claim as originally submitted. Please respond within 30 days with your decision and explanation.
Thank you,"
Attach copies of your supporting documents (not originals). Keep copies for yourself. Submit via the method insurance specifies—mail, fax, or online portal, depending on their preference.
What happens next: Insurance typically reviews internal appeals within 30 days for routine matters, up to 72 hours for urgent cases. They'll send you a written decision. If approved, great. If denied again, move to external review.
Step 2: Request an external review
If your internal appeal is denied, you have the right to an external review. This means an independent third party (not your insurance company) reviews your case. External reviews are free.
Who requests it: You can request the external review, or your doctor can request it on your behalf. Ask your doctor to do so if possible—insurance companies often take physician requests seriously.
What triggers external review eligibility: You're usually eligible if your claim was denied for medical necessity reasons. You're less likely to be eligible if you were denied for being out-of-network (unless your state's law provides for review in that case).
How to request: Ask your insurance company: "I want to request an external review of this denial." They must tell you how to submit. Some provide a form. Some allow submission to an independent review organization (IRO) directly. Your state may also have a process outlined in insurance regulations.
Timeline: External review typically takes 20–30 days. It's faster than litigation and more impartial than your insurer's own appeal process.
The outcome: The external reviewer issues a written decision explaining whether the service was medically necessary and whether insurance should cover it. If the reviewer agrees with you, insurance must pay. Their decision is binding.
Special case: surprise billing disputes
Surprise bills happen when you receive emergency care (or sometimes non-emergency care) from an out-of-network provider while in-network facility. You're unexpectedly hit with out-of-network charges.
Surprise billing disputes work slightly differently. Federal law now requires insurers to cover out-of-network emergency care at in-network rates. If you received emergency care and were balance-billed (sent a bill for the difference between the out-of-network charge and what insurance paid), you have strong legal ground to dispute.
What to do: Contact both your insurance company and the provider's billing department. Tell them: "This was emergency care [or cite the federal law if non-emergency at in-network facility]. Under federal law, I shouldn't be balance-billed for out-of-network emergency care. Please adjust the balance."
If the provider won't budge, file a complaint with your state insurance commissioner. Federal surprise billing protections are strong, and state regulators take these complaints seriously. You may also want to check our guide on what to do about out-of-network bills.
When to get help
Sometimes your appeal gets denied twice, or the case is complex, or you just don't have time to manage it. That's when outside help makes sense.
Options: Patient advocates (sometimes free through your hospital), medical billing advocates (paid), attorneys specializing in insurance disputes (usually on contingency), or specialized services that handle disputes professionally.
Your state insurance commissioner: If you've exhausted insurance appeals and still disagree, you can file a complaint with your state's insurance department. They have authority to investigate insurance company violations and can pressure companies to reverse unfair denials. This step is free and often effective.
Before paying a medical bill that insurance denied, understand the difference between your EOB and the hospital bill. Make sure the provider isn't double-dipping or billing incorrectly on top of the insurance issue.
For guidance on handling surprise bills in the first 48 hours, check our separate guide. And if your dispute involves out-of-network charges related to the No Surprises Act, federal protections are on your side.
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