A letter arrives saying the treatment your child's doctor ordered is "not medically necessary." Your family has been waiting months for that surgery, that equipment, that medication, that specialist. The phrase reads like a medical judgment about whether your child needs care, and that is the first thing to set aside, because the phrase is a contract term. Somewhere in your plan documents there is a written definition of medical necessity, and a reviewer decided the paperwork in front of them did not match it.

That distinction changes what you do next. Instead of persuading anyone that your child is sick enough, you are showing that the documented facts satisfy a definition the insurer wrote down and is bound by.

Get the File Before You Write Anything

The denial notice itself is required to tell you the specific reason for the decision, the rule or clinical criteria the plan applied, your right to appeal, and how to file. A notice that says only "not medically necessary" without naming the criteria is incomplete, and you should say so in writing.

Then ask for the rest. If your coverage comes through an employer plan governed by ERISA, you have the right to a free copy of everything the plan relied on: the internal guideline or medical policy used, the claim file, and the qualifications of any reviewer who weighed in. Ask in writing and keep the date, using the phrase "request for the complete claim file and any internal rule, guideline, or protocol relied upon."

Two documents matter most. The first is the plan's own definition of medical necessity, which lives in the summary plan description or evidence of coverage. The second is the clinical policy for the specific service, often a numbered document with criteria laid out in bullets. Families are usually surprised by how mechanical those criteria are: a required trial of a lesser treatment, a diagnostic code, a measurement threshold, documentation of a specific duration. Once you can read them, you can see exactly which line the claim fell short on.

Find Out Who Regulates Your Plan

Two systems govern appeals, and knowing yours determines where you can escalate.

Self-funded employer plans are governed by ERISA and overseen by the federal Department of Labor. Your state insurance commissioner has no authority over them. Fully insured plans, individual marketplace coverage, and small-group policies are regulated by your state's insurance department, which gives you a state complaint route and often stronger state-specific protections such as autism coverage mandates or step-therapy override laws.

Ask your human resources or benefits office whether the plan is self-funded or fully insured. Medicaid, Medicaid managed care, Medicare Advantage, and CHIP each run their own appeal systems with different deadlines and a fair-hearing right, so confirm the process for the coverage that issued the denial.

The Deadlines That Control Everything

You have 180 days from the date of the denial notice to file an internal appeal under ACA and ERISA rules. That is the clock that ends your options if it runs out, and phone calls between your doctor's office and the insurer do not pause it.

The plan's own response deadlines run 72 hours for urgent care requests, 30 days for treatment not yet received, and 60 days for a service already provided. If the delay itself would seriously jeopardize your child's health or ability to regain maximum function, you can request an expedited appeal and pursue external review at the same time rather than waiting.

One protection gets missed often: when a plan is cutting off or reducing an ongoing course of treatment that it previously approved, coverage generally continues while the internal appeal is pending, if you appeal before the reduction takes effect. Ask for that in the same letter.

The Provider Letter That Does the Work

A letter of medical necessity fails when it describes your child warmly and never touches the insurer's criteria. It succeeds when it walks through those criteria in order and answers each one with a fact from the chart.

Bring the clinical policy to the appointment and ask your provider to address, point by point:

• The diagnosis with its ICD code, and how it was established
• The specific service requested, with procedure codes, frequency, and expected duration
• What has already been tried, for how long, and what happened
• Why alternatives the policy names as first-line are inappropriate or already exhausted, in this child's case
• The functional consequence of not treating, described concretely: aspiration risk, skin breakdown, loss of ambulation, regression in communication, hospitalization
• Objective measures, including standardized assessment scores, growth data, seizure counts, or range-of-motion figures

Attach the underlying records rather than summarizing them, since progress notes, evaluation reports, therapy data, and photographs of a wound or a poorly fitting device carry more weight than adjectives. If your child has multiple providers, a short letter from each is stronger than one long letter from a physician who has not observed the daily reality.

Bring the Evidence Base With You

Denials for disability-related care often rest on a claim that the treatment is experimental, or that evidence does not support it for this population. Answer that on its own terms.

Professional society guidelines are the most useful material, because they carry consensus weight and are easy for a reviewer to verify. Add peer-reviewed studies for the specific indication with full citations and copies of the abstracts. Two or three directly relevant sources do more than a stack of loosely related ones. When the plan covers the same service for a different diagnosis, name that inconsistency.

You can also request that the appeal be reviewed by a clinician with training and experience in your child's condition who had no part in the original decision. Plans must consult an appropriate professional on medical judgment denials, and asking for the reviewer's specialty by name puts that requirement on the record.

External Review Moves the Decision Outside the Plan

After the internal appeal is exhausted, you generally have four months from the final denial to request external review by an Independent Review Organization. The reviewers are clinicians with no financial relationship to your insurer, decisions arrive within 45 days or 72 hours for expedited cases, and the outcome binds the plan. State-regulated plans use the state process, and self-funded plans use the federal one, with the denial letter naming the correct path.

Send the same package you sent internally, plus anything new: an updated provider letter answering the reasoning in the final denial, records showing what happened during the delay, additional literature. A short cover letter that lists each stated denial reason and points to the document that answers it makes the reviewer's job easy.

Other Levers Worth Pulling in Parallel

Some medical necessity denials are really something else wearing that label. Limits on behavioral health or autism services that are stricter than the limits on comparable medical care may violate federal parity rules. A refusal grounded in assumptions about quality of life with a disability may be a civil rights matter for the HHS Office for Civil Rights. Denials that conflict with a state mandate belong in front of the state insurance commissioner.

Specific services have their own well-worn paths. Therapy denials for speech, OT, or ABA services turn on parity arguments and progress documentation. Power wheelchair denials hinge on in-home mobility standards and the supplier's paperwork. A denied autism or ADHD evaluation often involves a plan carving diagnostics out to a behavioral health vendor. Funding for an AAC device may come faster through Medicaid or a grant program while an appeal is running.

Keep a Record As You Go

Every appeal that succeeds looks the same in hindsight: a dated log of calls with names and reference numbers, letters sent by a method that proves delivery, and copies of everything submitted. Reviewers change, files get reassigned, and the family holding the complete record is the one who can show that a deadline passed or a document was never considered.

If the external reviewer sides with the insurer, what remains is the appeal system of a different payer, a state complaint, a legal aid organization with health insurance experience, or an attorney who handles ERISA benefit claims. Your provider's office can also restart the request with the documentation the criteria demanded, and a second submission built on the clinical policy has better odds than the first one did.