What your doctor should put in a letter of medical necessity
A denial often says "not medically necessary." Your doctor is the person best placed to answer that, in writing, and you can hand them the list.
CheckMyDenial team, patient billing and appeals. Published October 2026. Last reviewed 2026-10-29.
What is a letter of medical necessity?
It is a letter from your doctor that explains why you need the care your insurer denied. HealthCare.gov lists a letter from your doctor as one example of extra information you can send with an internal appeal.
You are not alone in this. Going back to your doctor for help after a denial is a normal part of the appeal process.
What should my doctor put in the letter?
A good letter is clear and specific. Ask your doctor to include: your name, date of birth, and insurance ID; the exact service or item that was denied; your diagnosis in plain words; what you have already tried; why this care is needed for you; and what could happen if you go without it.
Also ask them to mention the claim or reference number from your denial letter, so it is matched to the right file. Bring a copy of the denial with you.
How do I ask my doctor for one?
You can do this in four short steps.
Keep it friendly. A clear, specific request with the denial attached makes it easier for the office to help you.
- Step 1: Gather your papers. Get your denial letter, insurance ID, and claim or reference number. Note the deadline written on the denial.
- Step 2: Contact your doctor's office. Call or use the patient portal. Say you are appealing a denial and would like a letter of medical necessity.
- Step 3: Hand over the checklist and denial. Give them the printed checklist and a copy of the denial so the letter answers the reason the insurer gave.
- Step 4: Send it with your appeal. Ask for a copy for yourself, then send the letter to your insurer with your appeal before the deadline.
How long do I have to appeal a denied claim?
It depends on the kind of plan you have, so your denial letter is the first place to look for your exact date.
For many health plans, such as marketplace plans and many employer plans, HealthCare.gov says you must file an internal appeal within 180 days (6 months) of receiving notice that your claim was denied. Some older plans and some employer plans can follow different rules, and Medicaid has its own process, so check your plan documents or call your insurer.
If you have Medicare Advantage or another Medicare health plan, Medicare.gov says the appeal must be filed within 65 days from the date on the initial denial notice. If you miss that deadline, you must give a reason for filing late.
What if I need care fast and cannot wait?
If waiting could seriously harm your health, you can ask for a fast (urgent) appeal. In a Medicare health plan, Medicare.gov says the plan must give its decision within 72 hours in that case. For a service you have not received yet, your doctor can also ask the plan to reconsider on your behalf, and must let you know.
For other health plans, HealthCare.gov says an urgent appeal decision must come as quickly as your medical condition requires, and within 4 business days after your request is received. Ask your doctor to say clearly in the letter that the situation is urgent.
What if the insurer says no again?
For many health plans outside Medicare, you may be able to ask for an independent outside review, called an external review. CMS says you must file a written request within sixty days of the insurer's final denial, and some states or plans allow more time. If you have coverage through work, you may have to file two internal appeals first. Check your final denial notice for the exact steps and date.
The insurer must explain in writing why it denied the claim, and the final denial must tell you how to request an external review. If your claim cannot go to external review, you can still ask your state's department of insurance or consumer assistance program for help. Medicare health plans have their own next levels of appeal, which your plan's notice will explain.
Your checklist
- My full name, date of birth, and insurance ID
- The claim or reference number from my denial letter
- The exact service or item that was denied
- My diagnosis in plain words
- What I have already tried, and what happened
- Why this care is needed for me, and what could happen without it
- The appeal deadline, and whether it is urgent
A letter you can copy
Dear Dr. [Doctor's last name], My insurance company, [insurance company name], denied coverage for [service, test, or item] on [date of denial]. The claim or reference number is [claim number]. I am appealing, and I would be grateful if you could write a letter of medical necessity to send with my appeal. It would help if the letter included: - My name, date of birth, and insurance ID: [your name], [date of birth], [insurance ID] - Why [service, test, or item] is needed for my [diagnosis] - What I have already tried: [treatments tried] - What could happen if I do not get this care - If it is urgent, a clear note saying so My appeal deadline is [deadline date], so I would appreciate the letter by [date]. I have attached a copy of the denial. Please send me a copy of the letter as well. Thank you for your help. [Your name] [Phone or email]
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. Medicare.gov: Appeals in a Medicare health plan. CMS: Has your health insurer denied payment for a medical service? You have a right to appeal. More in the full appeal guide.
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Free tools for the next step
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