You opened the denial letter, and your stomach dropped. The claim was denied. Maybe it’s a $4,200 surprise bill from a procedure you thought was covered. Maybe it’s a medication your doctor said you need. Whatever the service, the denial doesn’t feel like a judgment call. It feels final. It isn’t. A health insurance claim denial is not the end of the road. It is the beginning of a process that, when done correctly, results in overturned denials at a rate that should make every patient want to appeal before paying anything.
Federal law requires health insurers to provide a formal appeals process for every denied claim. Independent external reviewers, who have no financial relationship with your insurer, overturn a substantial portion of the denials they review. Studies have found external review overturn rates of 40 to 60 percent depending on the type of denial and the clinical area. Those numbers mean that in many cases, the insurer’s initial denial is not the final word on whether your care is covered. It’s a first draft that can be rewritten.
What determines whether an appeal succeeds is largely about documentation, understanding the type of denial you’re dealing with, meeting your deadlines, and pushing through each level of the process rather than stopping at the first rejection. Most people give up after the first denial. That’s exactly what the system is structured to encourage. Don’t be one of them.
Read the Denial Notice First
Before you do anything else, read the denial notice carefully. Your insurer is required by law to send you a written denial that states the specific reason for the denial, the specific plan provision or clinical criterion it’s based on, and information about your right to appeal, including deadlines and where to send your appeal. This letter is your roadmap. The denial reason determines your appeal strategy.
The four most common denial types are medical necessity, administrative, coverage, and coding. Medical necessity denials say the service wasn’t medically necessary according to the insurer’s clinical criteria. Administrative denials happen for procedural reasons: a missing referral, a provider not enrolled in the network, a service performed outside an authorization window, or missing claim information. Coverage denials say the service isn’t a covered benefit under your plan. Coding denials occur when the procedure or diagnosis codes on the claim don’t match what the insurer’s system expects for your diagnosis or service type.
Each denial type calls for a different response. A medical necessity denial calls for clinical evidence and physician involvement. An administrative denial may be resolved with a simple correction and resubmission. A coverage denial requires verifying your plan’s terms before deciding whether to appeal. A coding denial may be best addressed by asking your provider’s billing office to review and correct the codes before a formal appeal is necessary.
Level 1: Filing the Internal Appeal
The internal appeal is the first formal step. Your insurer must conduct this review using different personnel than those who issued the original denial. For most non-grandfathered health plans, you have 180 days from the date you receive the denial to file an internal appeal. Don’t wait that long. File as quickly as you can with the strongest documentation you can assemble.
For a medical necessity denial, the appeal package should include a letter from your treating physician explaining in clinical detail why the denied service is medically necessary for your specific condition. This isn’t a generic letter. It should reference your diagnosis, your treatment history, why less expensive alternatives are either inappropriate or have already been tried and failed, and cite relevant clinical guidelines from your physician’s specialty association. Attach copies of medical records that document the clinical picture. Published peer-reviewed literature supporting the use of the denied service for your diagnosis strengthens the appeal, though it’s not required.
For an administrative denial, gather the documentation that addresses the specific administrative gap. If the claim was denied for a missing referral, provide evidence that a referral was in place. If the denial was based on network status, provide documentation of your provider verification, such as a screenshot of the insurer’s directory at the time you used the provider, or a written confirmation from the provider’s office. If the denial was based on a missing authorization, investigate whether authorization was actually obtained by your provider’s office and, if so, submit proof.
The Peer-to-Peer Option for Medical Necessity Denials
Before or alongside the formal internal appeal, your treating physician can request a peer-to-peer review with the insurer’s medical reviewer who issued the denial. This is a direct phone conversation between your doctor and the insurer’s doctor. It’s not a formal appeal step, but it’s often more effective than the written appeal alone.
Peer-to-peer reviews have notably high reversal rates for initial medical necessity denials. The reason makes intuitive sense. A written prior authorization request can only convey so much about a patient’s clinical situation. A conversation between two physicians allows your doctor to provide context, answer questions in real time, and advocate directly for the clinical appropriateness of the treatment. If your claim was denied for medical necessity, ask your physician’s office immediately whether they can request a peer-to-peer. Some denials are reversed at this stage without ever requiring a formal appeal filing.
Document that the peer-to-peer was requested, when it was scheduled, who participated, and what the outcome was. If the insurer reverses the denial following the peer-to-peer, request written confirmation of the coverage determination. Verbal reversals that aren’t followed by written confirmation occasionally fall through the cracks administratively, and you want documentation of the approved status before the claim is reprocessed.
Expedited Internal Appeals for Urgent Cases
When your health would be seriously jeopardized by waiting for a standard internal appeal timeline, you can request an expedited appeal. Insurers must complete expedited internal appeals much faster than standard reviews, generally within 72 hours. For concurrent review denials, where an insurer has decided to stop covering a service you’re currently receiving, you can request continuation of that benefit while the expedited appeal is processed.
Expedited status requires documentation of the urgency. Your physician’s statement that your health or safety would be adversely affected by waiting is the typical basis. Be explicit in your request. Write “Expedited Review Requested” on all correspondence. Document the request date. Follow up promptly if you don’t receive a response within the required window. When time is a factor, every hour of delay in the process matters, and being proactive about pushing the appeal forward is part of your job in the process.
Level 2: Independent External Review
If your internal appeal is denied, or in certain urgent situations where you can skip the internal appeal, you can request independent external review (IRO). For most ACA-compliant health plans, the right to external review is guaranteed by federal law. The external reviewer is completely independent of your insurer. They review your case, the insurer’s denial, and all documentation submitted by both sides, and they issue a binding decision.
Binding means binding. If the external reviewer overturns your insurer’s denial, your insurer must cover the service or reimburse you for costs you’ve already paid. They can’t appeal the external reviewer’s decision back to themselves. This is why external review is the most powerful level of the appeals process, and why denials for medical necessity, where external reviewers consistently overturn a meaningful share of insurer decisions, are always worth taking all the way through the process.
For medical necessity denials, external review must be conducted by a clinical reviewer with relevant expertise in the medical condition or service at issue. You have the right to submit additional documentation and arguments. The standard external review decision comes within 45 days of your request. Expedited external review, for urgent situations, must be completed within 72 hours. File your external review request promptly after an internal appeal denial. Deadlines are typically four months from the internal appeal denial, though check your specific plan documents for the exact deadline. Missing the deadline forfeits the right to that review level.
State Insurance Commissioner Complaints
Filing a complaint with your state’s insurance department is an additional avenue that runs in parallel with the formal appeals process, not as a replacement for it. State insurance departments regulate insurers operating in their states and investigate consumer complaints about improper claims handling. If your insurer is processing your claims outside of required timelines, issuing denials without adequate explanation, or violating state insurance regulations, a complaint with the commissioner creates a regulatory record.
Your individual complaint won’t necessarily resolve your specific claim through the regulatory process. But it may prompt contact from the commissioner’s office with the insurer that helps move your situation forward. And patterns of complaints about the same insurer can trigger broader regulatory scrutiny and enforcement actions. It costs you nothing to file and takes less than an hour. For employer-sponsored ERISA plans, state regulation doesn’t apply to the plan itself, though federal external review rights do. ERISA complaints go to the U.S. Department of Labor, and persistent violations of ERISA claims procedure regulations can result in DOL enforcement action.
How to Build a Winning Appeal File
The appeals process rewards organization. From the moment you receive a denial, treat the claim as a file you’re building. Keep the denial notice. Record every phone call with your insurer: the date, the time, the representative’s name, and what was said. Send written communications wherever possible rather than relying entirely on phone conversations, and save copies of everything you submit.
If you’re mailing appeal documents, send them certified mail with return receipt requested. If submitting electronically, save the submission confirmation. The appeals process can extend over months, and disputes sometimes arise about what was submitted and when. Your paper trail is your protection against those disputes. Insurers have institutional memory and documentation systems. You need yours to be just as solid.
When to Ask for Help
You don’t have to navigate this alone. Patient advocates, either professionals you hire or nonprofits that provide free services, can help you assemble appeals and navigate the process. Your state insurance department often has a consumer assistance program that can provide guidance and, in some cases, active help with appeals. Your employer’s HR department may have a benefits advocate or third-party administrator contact who can help escalate insurer issues on your behalf. Hospital billing departments and social workers are sometimes experienced with appeals for claims related to hospital care and can be valuable allies.
For complex or high-dollar claims, the investment in professional help often pays for itself many times over. A patient advocate who successfully appeals a $25,000 denial earned their fee. If your insurer is denying a claim you believe is clearly covered, and the internal appeal didn’t resolve it, don’t assume the external review is too complicated to pursue on your own. It usually isn’t. The external review process is designed to be accessible to patients, and the organizations conducting external reviews are required to evaluate the clinical facts, not your ability to write a compelling legal argument. Your physician’s documentation and your plan’s terms are what matter. Get both in front of the reviewer and let the process work.