Denied as "experimental or investigational"? Here is what it means and how to push back.
"Experimental" is a label the plan chose, and it is not the final word. You are allowed to appeal it and ask the plan to explain it. You are not alone, and this denial can be worth fighting.
CheckMyDenial team, patient billing and appeals. Published October 2026. Last reviewed 2026-10-29.
What does "denied as experimental or investigational" actually mean?
It means your plan decided the treatment is not yet proven enough to cover. Plans make that call using their own written policies, so two plans can treat the same care differently.
The label is the plan's decision. It is not the final word, and you have the right to appeal it. You are not alone: many families see this wording on a denial letter.
Can I appeal an experimental denial?
Yes. Healthcare.gov lists a treatment the plan calls "experimental" or "investigative" as one of the reasons a denial can be appealed. It also says insurers have to tell you why they denied your claim and how you can dispute the decision.
If the plan still says no after its own review, healthcare.gov says the denial can go to an independent external reviewer, and that includes denials based on a finding that a treatment is experimental or investigational.
How long do I have to appeal?
For an internal appeal with a private health insurer, healthcare.gov says you must file within 180 days (6 months) of receiving the denial notice. Check the date on your letter today and write it on your calendar.
After your insurer's final denial, healthcare.gov says you have 4 months from when you receive that notice to ask for an external review.
These are the timelines healthcare.gov gives for private health insurance. Medicare, Medicaid, and some job-based or dental-only plans can use different steps and deadlines, so always go by the dates on your own denial letter.
How do I ask the plan for its criteria and the evidence it used?
Put the request in writing and keep a copy. Ask the plan to send you the written policy or guideline it used to call your treatment experimental, and the studies or reviewer notes behind the decision. Plans have to tell you why they denied a claim, and a written request gives you a paper trail.
The steps below are a practical way to do it. This is general information, not legal or medical advice.
- Step 1: Find the dates and numbers. On your denial letter, circle the date, your claim number, your member ID, and the exact reason given.
- Step 2: Write to the plan. Ask for the written criteria they used to call the treatment experimental or investigational, and the evidence or reviewer notes behind the decision. Send it by a method that gives you proof of delivery.
- Step 3: Ask your treating doctor for a letter. Ask the doctor treating you to explain in writing why this care is right for you, and to attach published studies or guidelines that support it.
- Step 4: File the appeal before the deadline. Send the appeal with the doctor's letter and the plan's own answers. Healthcare.gov says to include your name, claim number, and health insurance ID number, and you can add information such as a letter from your doctor.
How fast does the plan have to answer my appeal?
For private health insurance, healthcare.gov says internal appeals for services you have not received yet must be completed within 30 days, and for services you already received within 60 days.
If your case is urgent, healthcare.gov says the decision must come within 4 business days after your request is received. In urgent cases you can also file the internal appeal and an external review request at the same time.
What is an external review and does the plan have to follow it?
An external review means an independent reviewer, not your insurer, decides the case. Healthcare.gov says your insurer is required by law to accept the external reviewer's decision.
Standard reviews are decided no later than 45 days after the request is received, and expedited reviews within 72 hours or less depending on how urgent the case is. Healthcare.gov says it is free under the process run by HHS, and under other processes the charge cannot be more than $25.
Whether your state or HHS runs the review depends on where you live and your plan. Medicare and Medicaid have their own appeal processes.
I have Medicare. Is it different?
Yes. Medicare.gov says there are generally 5 levels of appeals, and the plan must tell you in writing how to appeal. At each level you get a decision letter with instructions on how to move to the next level.
Your State Health Insurance Assistance Program (SHIP) offers free, personalized counseling. You can find yours at shiphelp.org.
What if I just have my denial letter and do not know where to start?
Text a photo of your denial letter to (213) 606-6303. We read it and reply with where it breaks. It is free, with no account and no form.
Your checklist
- Write down the date on your denial letter
- Circle your claim number and member ID
- Note the exact reason the plan gave
- Write to the plan asking for its criteria and evidence
- Ask your treating doctor for a letter with published support
- File the appeal before the deadline on your letter (180 days for most private health insurance)
- Keep copies of everything you send and receive
A letter you can copy
[Date] [Plan name] Attn: Appeals / Grievances [Plan address or fax] Re: Request for coverage criteria and appeal Member name: [Your name] Member ID: [ID number] Claim number: [Claim number] Date of denial letter: [Date] Treatment denied: [Name of treatment or service] To whom it may concern, My claim was denied as experimental or investigational. I am appealing this decision. Please send me, in writing, the policy or guideline you used to decide this treatment is experimental or investigational, and the evidence or reviewer notes behind the decision. My treating doctor, [Doctor name], has written a letter explaining why this care is right for me, and it is enclosed along with [published studies or guidelines the doctor named]. Please reply in writing by [date]. If my health is urgent, I ask for an expedited review. If this denial is upheld, please tell me how to request an external review. Sincerely, [Your name] [Phone] [Address]
Which rules apply to you?
The steps and deadlines on this page can differ by the kind of plan you have. Your own denial letter always comes first.
- Coverage through a job:ask your HR team whether the plan is “self-funded” or “fully insured.” It can change who you can ask for help. Most private-sector job plans fall under a federal law called ERISA, and the U.S. Department of Labor’s EBSA takes health plan questions at Ask EBSA or 1-866-444-3272.
- Marketplace plan: follow the appeal steps at HealthCare.gov.
- Medicare or Medicaid: each has its own appeal process, listed on your notice.
- Dental-only plan: your plan contract sets the appeal rights, so read it and your letter.
Related answers
Sources: HealthCare.gov: Internal appeals. HealthCare.gov: External review. HealthCare.gov: Appealing a health plan decision. Medicare.gov: Appeals. More in the full appeal guide.
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Free tools for the next step
Keep your appeal papers in one place. Take a photo of your denial letter, EOBs and insurance cards with GetPreCare, so they are on your phone when the insurer or the office asks. Free. Open GetPreCare. Helping a parent or partner? Set it up for them.