Your insurer denied your MRI as “not medically necessary.” Your surgery pre-authorization came back rejected. Your prescription claim was turned down. You have the right to appeal — and a substantial share of medical necessity denials are reversed on internal appeal, especially when you submit additional clinical evidence like a specialist’s letter or updated test results.
An appeal is a formal request for your insurer to review its own denial decision. Federal law and most state regulations require insurers to offer a two-tier appeal process: an internal review first, then an independent external review if the internal appeal fails. The process is free, and you don’t need a lawyer to file. What you do need is a clear understanding of the timeline, the right evidence, and the specific policy language to cite.
Should you appeal or do something else first?
Not every denial requires an appeal. Before you start the insurance appeal process steps, identify what kind of denial you received:
File an appeal if:
- Insurer says the service was “not medically necessary”
- Insurer calls the treatment “experimental” or “investigational”
- Insurer denies coverage for an in-network provider or covered service listed in your plan
- Insurer denies pre-authorization for a procedure your doctor ordered
Resubmit the claim (not an appeal) if:
- Denial says “missing information” or “incorrect coding”
- Claim was denied for lack of prior authorization but you now have it
- Billing department entered the wrong diagnosis or procedure code
File a complaint with your state insurance commissioner if:
- Insurer missed its response deadline
- You suspect bad faith (pattern of denials, unreasonable delays)
- Billing or balance-billing dispute that’s not about coverage
If you’re unsure which route to take, your state’s Department of Insurance can clarify — find yours at the National Association of Insurance Commissioners state directory.
What you’ll need
Documents:
- Your denial letter (with the date you received it — this starts the clock)
- Your insurance policy or Summary of Benefits and Coverage (SBC)
- Explanation of Benefits (EOB) if the claim was processed
- Medical records supporting the denied service (test results, doctor’s notes, imaging reports)
- A letter from your doctor explaining why the service is medically necessary
Information to include:
- Your member ID, claim number, and the date of the denied service
- The specific policy section that covers the service (cite page and paragraph if possible)
- Published clinical guidelines or peer-reviewed studies supporting the treatment (especially for “experimental” denials)
Time investment:
- 1–2 hours to gather records and draft your appeal letter
- 30 days (standard) or 72 hours (urgent) for the insurer to respond
Understanding the claim appeal timeline
The clock starts on the date you receive the denial letter, not the date it was mailed. Keep the envelope with the postmark if you’re close to a deadline.
| Appeal Type | Your Deadline to File | Insurer’s Response Time |
|---|---|---|
| Internal Appeal (Standard) | 180 days from receipt of denial (federal); varies by state | 30 calendar days |
| Internal Appeal (Urgent) | File immediately if health is at risk | 72 hours |
| External Review (Standard) | 60 days after internal appeal denial | 30 calendar days |
| External Review (Urgent) | File immediately if delay risks health | 72 hours |
Source: Centers for Medicare & Medicaid Services (CMS) appeals guidance
Plan-type variation:
- Medicare Advantage: 60-day appeal window; CMS rules apply
- Original Medicare: Different process; use Medicare’s five-level appeal system
- Medicaid: State-specific timelines; often faster than commercial plans
- Employer plans (ERISA): Federal rules apply; contact your HR benefits team first
If your state requires a shorter or longer filing window, state law controls. Check your state insurance commissioner’s website for specifics.
Step 1: Read the denial letter and identify the reason
Your denial letter must state why the claim was denied. Common reasons:
- Not medically necessary — insurer’s medical reviewer disagrees with your doctor
- Experimental or investigational — insurer says the treatment lacks clinical evidence
- Not covered under your plan — service is excluded (cosmetic surgery, acupuncture, etc.)
- Out-of-network — provider wasn’t in your plan’s network
- Missing prior authorization — you or your doctor didn’t get pre-approval
The reason determines your appeal strategy. If the denial cites a policy exclusion (a service your plan never covers), the appeal is harder — you’ll need to argue the exclusion doesn’t apply or that the service falls under a covered category.
Step 2: Write your internal appeal letter
Your appeal letter should be short, factual, and cite specific policy language. Here’s the structure:
Header:
- Your name, address, member ID
- Claim number and date of service
- Date you’re filing the appeal
Body:
I am appealing the denial of [service or treatment] on [date]. The denial letter states the reason as [quote exact language from denial letter].
According to my policy [cite section, page number], [service] is a covered benefit when medically necessary. My physician, Dr. [name], has determined that [service] is medically necessary because [state medical reason — diagnosis, failed prior treatments, clinical guidelines].
Attached are:
- Letter from Dr. [name] explaining medical necessity
- [Test results, imaging, medical records]
- [Published clinical guidelines or peer-reviewed study, if applicable]
I request that you reverse this denial and approve coverage for [service]. Please confirm receipt of this appeal and provide a written decision within [30 days for standard, 72 hours for urgent].
Close:
- Your signature and date
- List of attachments
Send via certified mail or your insurer’s online appeal portal (if available). Keep a copy and the certified mail receipt.
Step 3: Submit new evidence
The internal appeal is your chance to submit anything that wasn’t in the original claim. Strong evidence includes:
- A detailed letter from your doctor — not just “patient needs this,” but “patient has X diagnosis, tried Y and Z treatments without success, clinical guidelines recommend this next”
- Peer-reviewed studies or clinical practice guidelines — especially for experimental-treatment denials; the Patient Advocate Foundation offers templates and research help
- Second opinion from a specialist — if your insurer’s denial cited a medical reviewer’s opinion
- Cost-effectiveness argument — if the denied service prevents a more expensive hospitalization or surgery later (frame this in your doctor’s letter)
Do not rely on emotional appeals alone. Insurers respond to policy language and clinical evidence.
Step 4: Wait for the internal appeal decision
Your insurer must assign the appeal to someone who did not make the original denial decision. If it’s a medical necessity denial, a physician reviewer (often in the same specialty) evaluates your case.
What you’ll receive:
- A written decision explaining the outcome
- If denied again, the reason why — with specific policy or clinical citations
- Instructions for filing an external review (the next level)
Reversal likelihood by denial type:
- Medical necessity denials: Often reversed when accompanied by specialist support and clinical guidelines
- Experimental/investigational treatment: Harder to reverse without robust clinical evidence from peer-reviewed sources
- Policy exclusions: Rarely reversed — the service was excluded from your plan’s coverage from the start
If your internal appeal is denied, you move to external review.
Step 5: File for external review if needed
An external review is handled by an independent organization with no financial tie to your insurer. It’s required by federal law for most plans and is free to you.
When external review is available:
- Your internal appeal was denied
- The denial involves medical judgment (not just billing or eligibility)
- Urgent cases where waiting for internal review could harm your health
When external review is NOT available:
- Billing disputes (wrong coding, missing info)
- Eligibility issues (you weren’t enrolled when the service occurred)
- Services your plan never covers (you’d need to argue the exclusion doesn’t apply, which is a legal question)
To request external review, contact your insurer or your state insurance commissioner. The external reviewer’s decision is binding in most states — the insurer must follow it.
Source: U.S. Department of Labor ERISA appeals process guidance
What appeals won’t fix
An appeal challenges the insurer’s coverage decision. It will not resolve:
- Billing errors — if the claim was coded wrong or missing information, ask your provider to resubmit a corrected claim
- Balance bills — if your provider is out-of-network and you owe the difference, that’s a separate complaint process; see your state’s surprise-billing protections
- Premium or eligibility disputes — contact your insurer’s member services or your state Department of Insurance
If your denial is for a service not covered under your plan — such as a cosmetic procedure or a service excluded in your policy — an appeal is unlikely to succeed unless you can argue the exclusion doesn’t apply. For example, if your insurer denied reconstructive surgery as “cosmetic,” but it’s medically necessary after an injury, cite the policy’s reconstructive-surgery provision.
For more on what your plan actually covers, see and .
When to call a professional
You can file an appeal yourself — the process is designed for consumers, and most succeed without legal help.
Consider hiring help if:
- Your internal appeal and external review were both denied, and you want to pursue legal action
- The denial involves a high-cost treatment (experimental cancer therapy, organ transplant) where the financial stakes justify legal fees
- You suspect bad faith (insurer repeatedly misses deadlines, denies without explanation, refuses to provide policy documents)
- You have a complex ERISA employer plan and the denial interpretation hinges on federal labor law
Resources:
- Patient advocates — some nonprofits offer free help; Patient Advocate Foundation provides appeal support and templates
- State insurance commissioner complaint line — free; can intervene if insurer violates state law
- Health insurance attorney — hourly or contingency; necessary only for legal disputes, not routine appeals
State and plan variation you need to know
Appeals rules differ by state and plan type. Key differences:
- Filing deadlines: Federal law sets 180 days for commercial plans, but some states allow more or less time
- Urgent appeal definitions: What counts as “urgent” varies; some states define it as “could cause serious harm,” others as “could impair a major body function”
- External review availability: A few states require external review before you can sue; others let you go straight to court after internal appeal
To find your state’s specific rules, visit the NAIC state insurance regulator directory and search for “health insurance appeals” or “external review process.”
If you have a Medicare Advantage plan, follow CMS rules (different from commercial plans). For Original Medicare Parts A and B, use Medicare’s five-level appeal system; see AARP’s Medicare appeals guide for details.
Employer plans (ERISA) follow federal Department of Labor rules and may require you to exhaust internal appeals before external review. Contact your HR benefits team first.
For network-related denials, plan type matters — HMOs require referrals and restrict out-of-network care more than PPOs. If your denial is network-related, see for context on how plan structure affects your appeal.
FAQ
How long does an insurance appeal take?
Standard internal appeals must be decided within 30 calendar days. Urgent appeals require a decision within 72 hours. External reviews follow the same timeline. If your insurer misses the deadline, file a complaint with your state insurance commissioner.
Can I appeal an insurance claim denial if I already paid the bill?
Yes. Paying the bill does not waive your right to appeal. If your appeal succeeds, the insurer will reimburse you (or pay the provider if you assigned benefits). Keep receipts and note the payment in your appeal letter.
What reasons can insurance use to deny a claim?
Common legal reasons include: not medically necessary, experimental treatment, service not covered under the policy, out-of-network provider, missing prior authorization, or claim filed after the deadline. The insurer must state the specific reason in your denial letter.
Do I need a lawyer to appeal an insurance claim?
No. Most people file appeals without a lawyer. You may want legal help if both internal and external appeals fail and you’re considering a lawsuit, or if the denial involves a very high-cost treatment.
Can insurance deny an appeal without explanation?
No. Federal and state law require the insurer to provide a written explanation citing the specific policy provision or clinical reason for the denial. If you receive a denial without explanation, file a complaint with your state insurance commissioner.
What happens if my appeal is denied?
If your internal appeal is denied, you can request an external review by an independent third party. If external review also denies your claim, your options are limited to legal action (suing the insurer) or paying out of pocket. External review decisions are binding in most states.
Most denials are reversed not because of loopholes, but because the insurer’s original reviewer lacked key evidence — a specialist’s letter, updated test results, or the correct policy citation. Gather that evidence, cite the policy, and file within the deadline. If the internal appeal fails, external review gives you a second, independent look at no cost. The process is procedural, not adversarial — and the timeline is on your side if you act quickly.
Not insurance or financial advice. This article explains the appeal process; it does not substitute for legal advice. If your appeal is denied and you believe it violates your policy or state law, consult an attorney or contact your state insurance commissioner.