What Is Medical Necessity?

What is medical necessity?

Medical necessity refers to whether a healthcare service is appropriate based on a patient's medical condition and accepted standards of clinical practice.

Health insurance companies, Medicare, Medicaid, and other health plans use medical necessity criteria when deciding whether to cover healthcare services.

Medical necessity reviews may apply to:

• Doctor visits
• Diagnostic tests
• Imaging studies
• Surgical procedures
• Prescription medications
• Durable medical equipment (DME)
• Physical therapy
• Home health services
• Behavioral health treatment

Even when a service is medically necessary, coverage also depends on the terms of the individual's health plan.

How is medical necessity determined?

Medical necessity is typically evaluated using several factors, including:

• Your medical history
• Symptoms and diagnosis
• Clinical evidence
• Accepted standards of medical practice
• Treatment guidelines
• The expected benefit of the service
• Whether less intensive treatment options are appropriate

Insurance companies often rely on physicians, nurses, pharmacists, or other clinical reviewers when evaluating medical necessity.

The specific criteria vary by health plan and benefit program.

Who decides whether care is medically necessary?

Medical necessity decisions involve both healthcare providers and health insurance plans.

Your healthcare provider recommends treatment based on your medical needs.

Your insurance company determines whether the recommended service meets the coverage requirements established under your health plan.

For government programs such as Medicare and Medicaid, medical necessity standards are governed by federal law, regulations, and program guidance, along with applicable contractor or state policies.

Why is medical necessity important?

Medical necessity plays a central role in determining whether insurance will pay for healthcare services.

If a service is determined to be medically necessary and all other coverage requirements are met, the insurer may approve coverage.

If a service does not meet the plan's medical necessity criteria, the claim may be denied or require additional documentation.

Medical necessity reviews help insurers evaluate whether healthcare services are appropriate based on clinical evidence rather than personal preference alone.

Medical necessity vs. prior authorization

These concepts are closely connected but serve different purposes.

Medical necessity

Determines whether a healthcare service is clinically appropriate and eligible for coverage under the health plan.

Prior authorization

Is the review process insurers use before certain services are provided.

Many prior authorization requests involve determining whether a service meets the insurer's medical necessity requirements.

Medical necessity vs. coverage

These terms are not interchangeable.

A service may be medically necessary but still not be covered under a particular health plan.

For example, a treatment may:

• Be excluded under the policy.
• Require prior authorization that was not obtained.
• Be performed by an out-of-network provider.
• Fall outside the plan's covered benefits.

Medical necessity is one factor in a coverage decision—not the only factor.

What happens if medical necessity is denied?

If an insurance company determines that a service is not medically necessary, it may deny coverage.

Depending on the plan, you or your healthcare provider may be able to:

• Submit additional medical records.
• Provide supporting clinical documentation.
• Request reconsideration.
• File an internal appeal.
• Request an external review if permitted under applicable law.

Many denials are resolved after additional information is submitted.

Common misconceptions

Myth: If my doctor says I need a treatment, my insurance company must cover it.

Reality: A healthcare provider determines what they believe is medically appropriate, but your insurance company separately determines whether the service meets your health plan's medical necessity and coverage requirements.

Why this matters

Medical necessity affects many healthcare decisions, from prescription medications and MRI scans to surgeries and medical equipment. Understanding how insurers evaluate medical necessity can help you prepare for prior authorization requests, understand claim denials, and work with your healthcare provider if additional documentation is needed.