How to appeal an insurance denial for surgery

Start with the denial letter. For employer plans under federal ERISA rules, the letter must give the specific reason for the denial and point to the plan terms it relied on. If the plan used an internal guideline, the letter must include it or say that a copy is free on request.

Beginning in 2026, Medicare Advantage plans, Medicaid and CHIP programs and insurers on the federal Marketplace are covered by a rule that says they must give a specific reason when they deny prior authorization.

The reason tells you what kind of appeal to write:

• Not medically necessary, or criteria not met. You answer the plan’s criteria point by point. See not medically necessary denials.
• No prior authorization. The surgery happened before approval. See denials for no prior authorization.
• Experimental or investigational. See experimental treatment denials.
• Excluded from coverage. If the plan document says it does not cover the procedure at all, an appeal arguing medical need usually has no rule to point to. Check the exact wording of the exclusion and the other routes on the plan exclusions page.

You are entitled to see the rules the plan applied to you.

• Employer plans. You can get free copies of all documents, records and other information relevant to your claim. That includes any plan policy on the denied treatment for your diagnosis, whether or not the reviewer relied on it, and the names of medical experts the plan consulted. Ask in writing.
• Medicare Advantage. Plans must follow Medicare’s national coverage determinations and other Traditional Medicare rules. They may write their own criteria only when Medicare’s are not fully established, and must publish them with a summary of the evidence. CMS told plans in 2024 that these criteria cannot be behind a paywall or require a subscription. You can read Medicare’s own national and local coverage decisions in the Medicare Coverage Database.
• Original Medicare. Prior authorization is rarely used in traditional Medicare, but there are exceptions. Hospital outpatient departments need approval in advance for a set list of procedures, among them blepharoplasty, rhinoplasty and vein ablation, plus cervical fusion with disc removal and implanted spinal neurostimulators. A demonstration applies prior authorization to five of the same procedure types at ambulatory surgical centers in 10 states, starting in January and February 2026. And a CMS model called WISeR, running from January 1, 2026 through 2031 in Arizona, New Jersey, Ohio, Oklahoma, Texas and Washington, requires prior authorization or a review before payment for services such as knee arthroscopy for knee osteoarthritis and electrical nerve stimulator implants. WISeR does not apply to Medicare Advantage.

Set your appeal up as a side-by-side: each criterion in the plan’s policy, and the page in your chart that shows you meet it. Ask your surgeon’s office for:

• Office notes showing how long you have had symptoms and how they limit daily life or work.
• Dates and results of treatments already tried, such as physical therapy, medications or injections, when the criteria call for them.
• Imaging and test reports that the criteria name.
• A letter of medical necessity from the surgeon that quotes each criterion and cites the record that meets it.

Send the records even if you think the plan already has them. When federal investigators reviewed Medicare Advantage denials, they found cases where plans said a request lacked documentation, “yet our reviewers found that the existing beneficiary medical records were sufficient” to support the service.

On appeal, an employer plan must consult a health care professional with training and experience in the field involved. A Medicare Advantage plan that expects to deny for medical necessity must first have the case reviewed by a physician or other professional with appropriate expertise, though not always one in your surgeon’s specialty.

A peer-to-peer review is a phone conversation between your surgeon and a doctor working for the plan, arranged by the surgeon’s office. One plan’s 2026 provider manual says the process lets the requesting physician talk directly with the plan physician who made the decision, and that further clinical information may be provided during the call.

Three things to know:

• It does not replace your appeal rights. The same manual says it “is not a prerequisite for a formal standard or expedited appeal.”
• The window can be short. One plan gives doctors’ offices five business days after a prior authorization denial to request one.
• At some plans, filing a formal appeal ends the option: “If you or the member file an appeal, a peer-to-peer review cannot be completed.”

Ask the surgeon’s office whether a peer-to-peer call was requested and what came of it. Keep the formal appeal deadline from your denial letter on your calendar either way.

Ask for an expedited decision when the standard timeline could seriously jeopardize your life, your health or your ability to regain maximum function. A Medicare Advantage plan must expedite an appeal when a physician says that standard is met and decide it within 72 hours. Employer plans must decide urgent appeals within 72 hours, and a treating doctor’s judgment that the claim is urgent binds the plan.

The first decision has a clock too. As of 2026, a Medicare Advantage plan must answer a standard prior authorization request within 7 calendar days and an expedited one within 72 hours. An employer plan has up to 15 days for a non-urgent request, with one possible 15-day extension.

If a Medicare Advantage plan refuses to speed up a request, it must move it to the standard track and send you a letter about your right to resubmit with a doctor’s support.

The next step is usually outside review. Insurance companies in all states must offer external review that meets federal standards.

It covers any denial that involves medical judgment. You must file within 4 months of the final internal denial, and the insurer must accept the reviewer’s decision. In urgent cases you can request external review at the same time as the internal appeal.

In Medicare Advantage you do not have to file the next level yourself. If the plan upholds its denial, it must send your case file to an independent reviewer contracted by CMS.

Deadlines and next steps differ by plan type. See Medicare Advantage, Original Medicare, employer plans, Marketplace plans and Medicaid.