What to Do When Your Insurance Denies a Treatment
The letter arrives — or the portal notification, or the explanation of benefits — and the language is clinical and definitive: the requested service has been denied. Not covered. Not medically necessary. Not authorized.
For patients who have just received a diagnosis, or who are waiting to begin a treatment their physician has recommended, an insurance denial can feel like a wall. The medical system, after what may have been a long road to get a clear recommendation, has produced a plan — and now the financial system is blocking it.
It is worth knowing, before anything else, that insurance denials are not final. They are the beginning of a process, not the end of one. Studies of insurance appeals consistently find that a meaningful proportion of denied claims are overturned on appeal — particularly when the appeal is well-documented and supported by clinical evidence. The insurance company's initial decision is made by reviewers working from limited information under time pressure. A well-constructed appeal, with the right documentation and the right framing, changes the information available for that decision.
Understanding how that process works — what the denial actually means, what the appeal involves, and how to build the strongest possible case — is something every patient should know before they accept a denial as the final word.
Reading the Denial Letter
The denial letter is the starting point, and it contains more useful information than it might appear to on a first read.
The first thing to identify is the reason for the denial. Insurance denials fall into several broad categories, and the category determines the appropriate response.
A prior authorization denial means the insurer required approval before the service was provided, and either that approval wasn't sought or it was sought and denied. Prior authorization is increasingly required for a wide range of services — specialist visits, imaging studies, certain medications, surgical procedures. When a prior authorization is denied, the stated reason — typically found in the denial letter or available through a call to the insurer — describes the basis for the denial and is the starting point for the appeal.
A medical necessity denial means the insurer has determined that the requested service is not medically necessary under their criteria. This is one of the most common denial reasons, and it is also one of the most frequently overturned on appeal — because "medically necessary" is a standard that requires clinical judgment, and the initial determination is often made by a reviewer without the full clinical picture.
A coverage exclusion denial means the service is specifically excluded from the patient's plan — either categorically (the plan doesn't cover this type of service) or conditionally (the plan covers it only under certain circumstances that the insurer believes are not met). Coverage exclusion denials are more difficult to appeal, because they raise a contractual question rather than a clinical one, but they are not always insurmountable — particularly when the exclusion is being applied incorrectly.
A coding or administrative denial means the claim was rejected for a technical reason — incorrect billing code, missing information, services billed in the wrong order, or a procedural error in how the claim was submitted. These denials are often the most straightforward to resolve, through correction of the underlying error rather than a formal appeal.
The denial letter must also specify the deadline for filing an appeal. These deadlines are real and matter — missing the appeal window can forfeit the right to contest the decision. The deadline should be noted immediately and treated as a hard constraint.
The Difference Between Internal and External Appeals
The appeals process has two stages, and understanding the distinction is essential to using it effectively.
An internal appeal is a request for the insurance company to reconsider its own decision. Every insurer is required, under the Affordable Care Act, to provide at least one level of internal appeal for denied claims. Some provide two. The internal appeal is reviewed by the insurer — typically by a different reviewer than the one who made the original decision, and in cases involving clinical judgment, by a physician reviewer.
The internal appeal is the first step and the appropriate starting point. It is also where the strongest clinical documentation should be submitted, because this is the stage at which new information most directly influences the outcome.
An external appeal is a review by an independent organization — a third-party entity that has no relationship with the insurance company — that evaluates whether the denial was appropriate under the terms of the plan and applicable law. External appeals are available after internal appeals have been exhausted, and in most states they are also available when an insurer has taken an unusually long time to respond to an internal appeal. The decision in an external appeal is binding on the insurer — meaning that if the external reviewer overturns the denial, the insurer must cover the service.
External appeals are a powerful tool that many patients don't know they have. The external reviewer is independent, and their standard of review is whether the denial was medically appropriate — not whether it was convenient or cost-effective for the insurer. Studies examining external appeal outcomes find that patients win a meaningful proportion of external appeals across most states and most denial categories.
Building the Appeal: What Documentation to Gather
A strong appeal is a clinical argument, not an emotional one. Insurance reviewers are evaluating whether the documentation supports the medical necessity of the requested service under the plan's criteria and under established clinical standards. The appeal needs to make that case in clinical terms, supported by specific evidence.
The core documentation for most medical necessity appeals includes the treating physician's letter of medical necessity — a document specifically written for the appeal that explains why this particular service is medically necessary for this particular patient, citing the specific clinical findings, the patient's diagnosis and history, the treatment guidelines that support the recommendation, and the anticipated harm of denial. This letter is the most important single document in the appeal, and it should be written specifically for the appeal rather than repurposed from other clinical correspondence.
Supporting clinical records should be included: relevant office visit notes, laboratory results, imaging reports, specialist consultations, and any other documentation that supports the clinical picture the physician's letter describes. The records should be organized and relevant — not a comprehensive dump of every document in the patient's file, but the specific clinical evidence that supports the medical necessity argument.
Relevant medical literature can strengthen a medical necessity appeal significantly. If the recommended treatment is supported by clinical guidelines from major professional organizations, or by peer-reviewed research demonstrating its effectiveness for the patient's specific diagnosis, including that evidence gives the reviewer a basis for finding that the denial was inconsistent with accepted clinical standards.
The insurer's own coverage criteria — typically available in the plan documents or by request — should be reviewed before the appeal is written. The appeal should specifically address the criteria the insurer used to deny the claim and explain why the patient's situation meets those criteria. An appeal that is framed around the insurer's own language is more persuasive than one that argues in general terms about what the patient needs.
How to Write the Appeal Letter
The appeal letter itself should be organized, specific, and clinical in its framing. Several principles guide effective appeal writing.
Lead with the conclusion. State clearly, in the opening paragraph, what is being appealed, why the denial was wrong, and what outcome is being requested. Do not bury the key argument in a narrative that the reviewer has to wade through to find.
Address the specific reason for the denial. Whatever reason the insurer gave for the denial, the appeal should respond directly to it. If the denial was based on a determination that the service is not medically necessary, the appeal should explain specifically why it is. If it was based on a coverage exclusion, the appeal should explain why the exclusion doesn't apply. A general appeal that doesn't address the specific denial reason is less persuasive than one that directly engages with what the insurer said.
Cite specific clinical evidence. The physician's letter, the relevant records, and the supporting literature should be referenced specifically in the letter. "As documented in the attached letter from Dr. [name], dated [date]..." is more persuasive than "my doctor says I need this."
Reference applicable standards. If the treatment being denied is recommended by major clinical guidelines — from organizations like the American Cancer Society, the American Heart Association, or relevant specialty boards — state that explicitly. A denial that is inconsistent with established clinical guidelines is vulnerable on appeal.
Keep the tone professional. The appeal letter is a clinical and administrative document, not an emotional one. Frustration and fear are understandable, but an appeal that is written in anger or that attacks the insurer's motives is less effective than one that makes a calm, well-documented clinical case.
When to Involve Your Doctor — and How
The treating physician's involvement is essential to most medical necessity appeals, and it is worth being direct with the physician about what is needed and why.
Most physicians are willing to write letters of medical necessity for appeal purposes — it is a standard part of practice — but the quality of those letters varies significantly. A letter that simply restates the diagnosis and says "this treatment is necessary" is less effective than one that specifically addresses the insurer's denial criteria, cites relevant clinical guidelines, explains the clinical reasoning behind the recommendation, and describes the anticipated harm of the denial.
Patients can help their physicians write stronger letters by providing a copy of the denial letter and the insurer's coverage criteria, explaining what specific argument the letter needs to make, and asking the physician to address the denial reason directly. Some physicians are experienced with insurance appeals and will know how to do this without guidance; others may benefit from the patient's specific input about what the appeal needs to accomplish.
Physicians can also request a peer-to-peer review — a conversation between the treating physician and the insurance company's medical reviewer, in which the physician can explain the clinical rationale for the recommendation directly. Peer-to-peer reviews overturn denials at a meaningful rate, and patients should ask their physician whether this option is available and appropriate for their situation.
The Role of a Patient Advocate
Navigating an insurance denial — understanding the reason, gathering the documentation, constructing a clinical argument, meeting the deadlines, and escalating to external appeal if necessary — is a process that requires time, organization, and some degree of familiarity with how insurance systems work. Many patients, managing this process while also managing an illness, find it genuinely difficult.
A patient advocate can provide meaningful support at several points in this process. At the most basic level, an advocate can help a patient understand the denial letter, identify the correct appeal pathway, and organize the documentation needed for a strong appeal. At a more substantive level, a physician-led advocate can help frame the clinical argument, identify the relevant medical literature, and work with the treating physician to ensure the letter of medical necessity addresses the specific criteria the insurer is using.
Pilot Rock Medical Navigators assists patients in navigating the insurance process as part of its broader patient advocacy work — helping patients understand what they're dealing with, what documentation strengthens their case, and how to engage the treating team in the appeal process effectively. For patients facing denials for significant treatments — a recommended surgery, a specialized medication, a specialist consultation at a major center — this kind of support can make a meaningful difference in the outcome.
It is also worth knowing that if internal and external appeals fail, additional options may exist: filing a complaint with the state insurance commissioner, seeking assistance from the state's insurance consumer advocacy office, or in some cases consulting with an attorney who specializes in insurance law. These paths are less commonly necessary, but they exist — and a patient who has been systematically denied coverage for a medically necessary treatment should know that the process does not end with an unsuccessful external appeal.
A Denial Is Not a Diagnosis
The insurance company's determination that a treatment is not medically necessary is not a medical opinion. It is an administrative decision, made by reviewers using criteria designed for population-level cost management, applied to an individual patient's clinical situation. That decision may be wrong — and a meaningful proportion of the time, it is.
The appeals process exists precisely because the initial determination is fallible, and because patients have a right to have that determination reviewed with the full clinical evidence in front of the reviewer. Using that process — promptly, methodically, and with well-organized documentation — is not an act of confrontation. It is an act of appropriate self-advocacy in a system that is imperfect and that benefits from patients who know how to navigate it.
The wall, on closer examination, usually has a door.
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If you or a loved one is facing an insurance denial for a recommended treatment and needs help understanding the appeal process or building a strong case, Pilot Rock Medical Navigators can help. Book a free 15-minute introductory call to discuss your situation. Learn how Pilot Rock can help →