Who this guide is for
This page focuses on commercial health insurance (employer or individual plans) in the United States. Medicare, Medicare Advantage, Medicaid/Medi-Cal, TRICARE, and VA benefits have different rules, forms, and timelines. Start at Getting Care to find the coverage guide that matches your plan type.
Act quickly
Many commercial plans allow a limited window to file an internal appeal—often up to 180 days from when you receive the denial notice. Your denial letter is the source of truth for deadlines. Do not wait.
Don't delay urgent medical care
If you have a sudden change in hearing (hours to 3 days), new severe vertigo, facial weakness/numbness, or other neurologic symptoms, seek urgent evaluation right away. Don't wait on insurance paperwork. See Emergency: Hearing, Tinnitus, and Balance Safety Guide.
When you receive an Explanation of Benefits (EOB) or a denial letter, it can feel like the process is over. In many cases, it is not. Some denials happen because the plan needs more information, the request didn't match the plan's medical policy criteria, or the claim was processed with incomplete documentation.
A practical first step: call the member services number on your insurance card and ask for the following, in writing when possible:
- The exact reason for denial (and whether it was a coverage decision vs. a coding/processing issue).
- The plan's medical policy or coverage criteria that applies to your request.
- Your deadline for an internal appeal and how to submit it (portal, mail, fax).
- Whether an expedited (urgent) review is available and what qualifies as urgent for your plan.
Decoding common denial codes
Denial letters often list standardized codes. The same code can show up for different services, so the code is a clue—not the whole story. The "strategy" below tells you what usually helps next.
| Code | What it often means | The strategy |
|---|---|---|
| CO-50 | Not medically necessary. The plan says the requested service/device/procedure does not meet their medical necessity criteria. | Ask for the plan's written medical policy and criteria. Your clinician can respond with targeted documentation: functional impact, objective test results, relevant diagnoses, and why the requested option fits the plan's criteria. |
| CO-151 | Documentation does not support the number or frequency of services. This often appears when multiple visits, therapy sessions, testing, or follow-up services are billed and the payer says the documentation doesn't justify the amount. | Your clinic may need to submit visit notes, goals, outcome measures, or an updated plan of care explaining why the frequency is needed. If it was a billing/coding issue, the clinic may correct and resubmit. |
| CO-97 | Bundled service. The payer says a billed charge is included in payment for another service/procedure already processed. | This is usually handled by the billing team: they may review the coding, documentation, and whether a corrected claim or additional detail is needed to show the service was separate and appropriate to bill. |
| CO-55 / CO-56 | Experimental / investigational or not proven effective. The plan says the evidence does not support coverage under their medical policy. This can come up with newer technologies, off-label uses, or treatments the plan considers unproven. | Ask for the plan's medical policy and what evidence they require. Your clinician may submit peer-reviewed evidence and consensus guidance when available. For devices, FDA labeling/clearance may be relevant context—but it does not guarantee insurance coverage. |
| PR-96 | Non-covered charge(s). The plan does not cover the item/service under the contract (for example, some plans exclude hearing aids). | Appeals are difficult if the benefit is truly excluded. Ask your plan if there are exceptions, riders, or alternate benefits. Consider secondary insurance, flexible spending/HSA funds, or financial assistance resources. |
Note: Denial codes can vary by insurer and claim type. Always match the code to the written explanation on your denial letter.
The strategy: the Letter of Medical Necessity (LMN)
If the denial is based on medical necessity (often CO-50), your clinician may submit a Letter of Medical Necessity (LMN). A strong LMN connects test results to real-world function, safety, and health impact—and directly addresses the insurer's criteria.
What should go in an LMN?
The most effective letters are specific. Depending on the request, an LMN may include:
- Diagnosis + objective findings: key audiology results (and, when relevant, speech understanding measures) tied to the insurer's criteria.
- Functional impact: concrete examples (work safety, communication needs, fall risk with balance issues, inability to hear alarms, etc.).
- Why this option: why the requested device/procedure is appropriate compared with alternatives (and what has already been tried, if applicable).
- Policy alignment: a point-by-point response to the insurer's medical policy criteria (attach the policy if helpful).
- When relevant: clinical guidelines/consensus and device labeling information (for implanted devices), without implying that FDA status guarantees coverage.
The appeal process: step-by-step (commercial insurance)
1) Ask for a reconsideration or clinician-to-clinician discussion (when available)
Some commercial plans offer a clinician discussion (often called a "peer-to-peer" conversation) before or during the formal appeal process. It is usually between your treating clinician and the insurer's clinical reviewer. This can be a fast way to clarify documentation needs or correct misunderstandings. Important: a clinician-to-clinician call may not help if the denial is a true benefit exclusion (for example, PR-96).
2) File the internal (first-level) appeal
If the denial stands, you (or your authorized representative) can submit a written internal appeal. Include the denial letter, the plan's medical policy criteria (if you have it), the LMN, and supporting documentation. For many plans, internal appeals have set timelines for decisions depending on whether the service is pre-service (not yet received), post-service (already received), or urgent.
- Tip: Keep copies of everything you submit and write down dates, names, and reference numbers from phone calls.
- Tip: If your plan allows portal upload, that can create a time-stamped record of submission.
3) Request an independent external review (if eligible)
For many commercial plans, if the internal appeal is denied, you can request an external review by an independent reviewer. Depending on your plan and the situation, the external review decision may be binding on the insurer. Urgent situations may qualify for an expedited timeline. Your denial letter (and plan documents) should explain how to request external review and the deadline to do so.
References
Key sources used to support timelines, appeal rights, and denial code definitions (accessed January 31, 2026 unless otherwise noted):
- X12. Claim Adjustment Reason Codes (CARC). (No posted publication date; accessed 2026-01-31.)
- HealthCare.gov. Internal appeals. (No posted publication date; accessed 2026-01-31.)
- HealthCare.gov. External review. (No posted publication date; accessed 2026-01-31.)
- Centers for Medicare & Medicaid Services (CMS). Appealing Health Plan Decisions. Page last modified 09/10/2024.
- eCFR. 45 CFR § 147.136 — Internal claims and appeals and external review processes. eCFR display “up to date as of 01/29/2026.”
- American Academy of Otolaryngology–Head and Neck Surgery Foundation (AAO-HNSF). Clinical Practice Guideline: Sudden Hearing Loss (Update). (Guideline update published 2019; page accessed 2026-01-31.)
- National Institute on Deafness and Other Communication Disorders (NIDCD). Sudden Sensorineural Hearing Loss (SSHL). (No posted publication date; accessed 2026-01-31.)
Bottom line
Denials are common—and many are reversible in commercial insurance when the appeal directly addresses the plan's criteria. Keep it specific: get the policy, match the documentation to the policy, and meet every deadline.
Next steps: get help with your denial
You don't have to navigate denial codes and appeal deadlines alone. Our billing specialists and templates can help you take the next step with confidence.