A letter of medical necessity (LMN) is a letter, usually from a doctor, that explains why a treatment, test, medication or device is needed to diagnose or treat a patient’s condition.
It names the patient, states the history and what was tried, and asks the health plan for one clear decision.
Below are 6 complete samples: 5 doctor letters for physical therapy, a migraine medication, a spine MRI, a glucose monitor and an intensive outpatient program, plus a letter from a patient asking a doctor to write one.
A free builder lets you tap, edit, print or copy your own letter. The doctors, patients, plans and details are fictional.
This page is general information, not medical or legal advice, and the treating doctor should review and sign any letter.
6 Medical Necessity Letter Samples
Quick jump: Physical therapyMedicationMRIGlucose monitorMental healthAsk your doctorFree medical necessity letter builder
Medical Necessity Letter for Physical Therapy After Knee Replacement
Lakeview Family Medicine, 400 Medical Plaza, Suite 200, Columbus, OH 43215
(555) 010-7421
November 14, 2026
Utilization Review Department
Prairie Health Plan
1200 Commerce Street
Omaha, NE 68102
Re: Letter of Medical Necessity: Physical Therapy
Patient: Robert Hayes | Member ID ending in 5521 | Date of birth 03/14/1961
Dear Utilization Review Team,
I am writing to support a request for 12 additional physical therapy sessions for my patient, Robert Hayes, after his total knee replacement on September 8, 2026. He has completed 12 sessions and improved his knee bend from 70 to 105 degrees.
He needs to reach at least 120 degrees to climb stairs safely, and his home has 14 steps to the bedroom. His therapist expects 2 sessions a week for 6 weeks to reach that goal, and he has followed his home program every day.
Stopping care now risks a stiff knee and a second procedure. I am asking you to approve the 12 sessions, and I am available for a peer-to-peer call.
Thank you for your time and consideration.
Sincerely,
Susan Patel, MD
Medical Necessity Letter for a Preventive Migraine Medication
Riverside Neurology Group, 88 Riverside Drive, Louisville, KY 40202
(555) 010-8532
November 14, 2026
Appeals Department
Prairie Health Plan
1200 Commerce Street
Omaha, NE 68102
Re: Letter of Medical Necessity: Preventive Migraine Medication
Patient: Karen Walker | Member ID ending in 7730 | Date of birth 08/22/1984
Dear Appeals Team,
This letter supports an appeal of your October 20, 2026 denial of a preventive migraine medication for my patient, Karen Walker. She has had 14 migraine days a month for 6 months.
She took two preferred medications at full doses for 3 months each and stopped one because of side effects. Her headache diary shows no more than a 10% drop in migraine days, and she has missed 9 days of work in 6 months.
The requested medication matches published guidelines for patients who do not improve on first-line options. I am asking you to reverse the denial, and I would welcome a call to talk it through.
Thank you for your time and consideration.
Sincerely,
Michael Turner, MD
Medical Necessity Letter for a Lumbar Spine MRI
Midland Orthopedic Clinic, 300 University Avenue, Minneapolis, MN 55455
(555) 010-9643
November 14, 2026
Expedited Appeals Department
Prairie Health Plan
1200 Commerce Street
Omaha, NE 68102
Re: Letter of Medical Necessity: Lumbar Spine MRI
Patient: Daniel Foster | Member ID ending in 4408 | Date of birth 11/05/1972
Dear Expedited Appeals Team,
My letter supports an expedited review of a lumbar spine MRI for my patient, Daniel Foster. He has had leg pain and numbness for 8 weeks that has not improved with 6 weeks of physical therapy and medication.
His exam shows weakness in his left foot, and his reflexes are reduced. These signs point to a nerve problem that can become permanent without a timely diagnosis.
Because delay could harm him, I am asking for a decision within the urgent timeline. Test results and my exam notes are attached, and I am available for a peer-to-peer call.
Thank you for your time and consideration.
Sincerely,
Rachel Hughes, MD
Medical Necessity Letter for a Continuous Glucose Monitor
Emily Carter, MD
Cardinal Endocrine Center, 700 Cardinal Plaza, Charlotte, NC 28202
(555) 010-1754
November 14, 2026
Utilization Review Department
Prairie Health Plan
1200 Commerce Street
Omaha, NE 68102
Re: Letter of Medical Necessity: Continuous Glucose Monitor
Patient: Jessica Miller | Member ID ending in 2216 | Date of birth 02/17/1990
Dear Utilization Review Team,
I am writing to request coverage of a continuous glucose monitor for my patient, Jessica Miller, who has had type 1 diabetes for 11 years and uses insulin 4 times a day.
Finger-stick checks have missed 3 overnight low readings this year, and she has had 2 emergency visits for low blood sugar. Her A1C is 8.4%, and her care team has set a goal of 7.0%.
Continuous monitoring gives alerts before a low reading becomes an emergency. I am asking you to approve the device, and my office will send her chart notes on request.
Thank you for your time and consideration.
Sincerely,
Emily Carter, MD
Medical Necessity Letter for an Intensive Outpatient Program
James Anderson, MD
Evergreen Behavioral Health, 2200 Camelback Road, Phoenix, AZ 85016
(555) 010-2865
November 14, 2026
Utilization Review Department
Prairie Health Plan
1200 Commerce Street
Omaha, NE 68102
Re: Letter of Medical Necessity: Intensive Outpatient Program
Patient: Maria Gonzalez | Member ID ending in 9054 | Date of birth 06/30/1991
Dear Utilization Review Team,
This letter supports a request for 8 weeks of an intensive outpatient program for my patient, Maria Gonzalez, who has severe depression that has not improved with weekly therapy and medication over 5 months.
Her symptom score has stayed at 21, which is in the severe range, and she has missed 12 days of work. She has no safety concerns that need hospital care, and a structured program 3 days a week is the right level of care.
The program lets her stay at home and keep working part time. I am asking you to approve the 8 weeks, and I would welcome a call from your medical director.
Thank you for your time and consideration.
Sincerely,
James Anderson, MD
Letter Asking Your Doctor for a Medical Necessity Letter
Thomas Reed
2716 Elm Avenue
Dayton, OH 45402
thomas.reed@email.com | (555) 010-3976
November 14, 2026
Dr. Susan Patel
Lakeview Family Medicine
400 Medical Plaza, Suite 200
Columbus, OH 43215
Re: Request for a Letter of Medical Necessity, Physical Therapy
Dear Dr. Patel,
I am writing to ask whether you would write a letter of medical necessity for 12 more physical therapy sessions. My insurer denied the request on October 20, 2026, and the denial letter says it needs a doctor’s letter to support an appeal.
The appeal deadline is 180 days from the date I received the notice, and I plan to file by December 1, 2026. I have attached the denial notice, my therapy notes and my claim number, and I have kept up my home exercises every day.
My therapist reports that my knee bend improved from 70 to 105 degrees in 12 sessions. Would you be able to send the letter by November 25, 2026? I am glad to stop by your office to sign any form you need.
Thank you for your time and consideration.
Sincerely,
Thomas Reed
Free Medical Necessity Letter Builder
Step 1. What does the patient need?
Step 2. Where are you in the process?
Step 3. Tap the lines to add. Three to five keeps the letter short.
Step 4. Click any text in the letter below and type or modify to make it yours.
The doctor or care team replaces the names, dates, history and test results with true information from the patient’s chart. Patients can bring this draft to the doctor, who should review, edit and sign it.
Susan Patel, MD
Lakeview Family Medicine
400 Medical Plaza, Suite 200
Columbus, OH 43215
(555) 010-7421 | office@lakeviewfm.example
November 14, 2026
Utilization Review Department
Prairie Health Plan
1200 Commerce Street
Omaha, NE 68102
Appeals Department
Prairie Health Plan
1200 Commerce Street
Omaha, NE 68102
Expedited Appeals Department
Prairie Health Plan
1200 Commerce Street
Omaha, NE 68102
Re: Letter of Medical Necessity: Physical Therapy
Patient: Robert Hayes | Member ID ending in 5521 | Date of birth 03/14/1961
Re: Letter of Medical Necessity: Preventive Migraine Medication
Patient: Karen Walker | Member ID ending in 7730 | Date of birth 08/22/1984
Re: Letter of Medical Necessity: Lumbar Spine MRI
Patient: Daniel Foster | Member ID ending in 4408 | Date of birth 11/05/1972
Dear Utilization Review Team,
Dear Appeals Team,
Dear Expedited Appeals Team,
I am writing to support a request for 12 additional physical therapy sessions for my patient, Robert Hayes, after his total knee replacement on September 8, 2026. He has completed 12 sessions and has improved his knee bend from 70 to 105 degrees, and he needs to reach at least 120 degrees to climb stairs safely.
I am writing to support coverage of a preventive migraine medication for my patient, Karen Walker. She has had 14 migraine days a month for 6 months and has not improved on two preferred medications taken at full doses for 3 months each.
I am writing to support a lumbar spine MRI for my patient, Daniel Foster. He has had leg pain and numbness for 8 weeks that has not improved with physical therapy and medication, and his exam shows weakness in his left foot.
I am asking you to approve this request before treatment begins.
I am asking you to reverse the denial dated October 20, 2026 on appeal.
Because delay could harm the patient, I am asking for an expedited decision.
This treatment follows accepted standards of care.
Lower-cost options have been tried without enough benefit.
Records and test results are attached.
Without this care, the patient is at risk of a longer recovery.
The patient has followed every part of the care plan.
The care is ordered to treat the condition and not for convenience.
This request matches published clinical guidelines for the condition.
I am available for a peer-to-peer call with your medical director.
The patient has made measurable progress so far.
I will send updated records on request.
Call my office with any questions.
Thank you for reviewing this request.
Thank you for your time and consideration.
Sincerely,
Susan Patel, MD
To save your letter: press Ctrl+P (Windows) or Cmd+P (Mac) and choose Save as PDF. Only the letter prints. To copy it, select the text inside the letter and press Ctrl+C or Cmd+C.
Which Sample Fits Your Situation?
| Your situation | Best sample | Key details |
|---|---|---|
| Therapy or a procedure needs approval | Samples 1 and 5 | Progress so far, the goal and the number of sessions |
| A medication or device was denied | Samples 2 and 4 | What was tried, results and the risk without it |
| Testing is urgent | Sample 3 | Exam findings and the reason a delay could harm |
| You need the doctor to write one | Sample 6 | The denial date, the deadline and the documents attached |
How to Get and Use a Medical Necessity Letter: 6 Steps
Step 1. Read the Denial Notice
Find the reason for the denial, the claim number, the deadline and the department to write to.
Step 2. Ask the Doctor to Write It
Doctors know the diagnosis and the standard of care. Ask for a letter and offer the sample above as a starting point.
Step 3. Gather Records
Collect chart notes, test results, therapy reports and a headache or symptom diary if one applies.
Step 4. Keep the Facts Specific
Include dates, numbers and what was tried. Specific facts are easier for a reviewer to approve.
Step 5. Send It With Your Appeal
Send the letter with your appeal, within the deadline, and keep copies of everything.
Step 6. Ask for an Urgent Review When Needed
If a delay could harm your health, ask for an urgent decision and tell the insurer why.
What to Include in the Letter
| Part | What to write |
|---|---|
| Clinic details | The doctor’s name, practice, address and phone number, plus the date |
| Recipient | The utilization review or appeals department on the denial notice |
| Re line | The care requested, the patient’s name, member ID digits and date of birth |
| Opening | A clear sentence stating the request and who the letter is about |
| History | The diagnosis, how long it has lasted and what has been tried |
| Why it is needed | Exam findings, test results and standards of care |
| Risk | What could happen without the care |
| Request | One clear ask: approve, reverse the denial or decide faster |
| Enclosures | Chart notes, test results and the denial notice |
| Close | A thank you, an offer of a peer-to-peer call and the doctor’s signature |
Appeal Facts From HealthCare.gov
| Topic | What HealthCare.gov says |
|---|---|
| Medically necessary | Services or supplies needed to diagnose or treat an illness, injury, condition, disease or its symptoms, and that meet accepted standards of medicine |
| Preauthorization | A decision that a service, drug or equipment is medically necessary; not a guarantee of coverage |
| Internal appeal deadline | 180 days (6 months) after you receive the denial notice |
| Internal appeal decision | 30 days if care is not yet received; 60 days if it was; 4 business days if urgent |
| Doctor’s role | A doctor’s letter can go with the appeal, and your doctor can file for you with a signed form |
| External review deadline | 4 months after the final denial notice |
| External review decision | 45 days; 72 hours or less if expedited; binding on the insurer |
| External review cost | No charge in the federal process; no more than $25 if a state or private reviewer is used |
Weak vs Strong Lines
| Weak line | Why it fails | Stronger line |
|---|---|---|
| The patient needs this | Gives no reason | She has had 14 migraine days a month for 6 months. |
| Other treatments failed | Names none | Two preferred medications failed at full doses for 3 months each. |
| This is urgent | Gives no facts | His exam shows weakness in his left foot. |
| Therapy is helping | Gives no number | His knee bend improved from 70 to 105 degrees. |
| Kindly approve | Leaves out the ask | I am asking you to approve the 12 sessions. |
Mistakes to Avoid
- Using vague wording. Add dates, numbers and what was tried.
- Leaving out the patient’s details. Add the name, member ID digits and date of birth.
- Missing the deadline. Check the date on the denial notice.
- Asking for several things. Make one clear request.
- Skipping the records. Attach chart notes and test results.
- Sending an unsigned letter. The treating doctor must review and sign it.
Medical Necessity Letter Checklist
Tick each item as you finish. Your letter is ready when the counter reaches 5.
Frequently Asked Questions
What is a letter of medical necessity?
A letter of medical necessity is a letter, usually from a doctor, that explains why a treatment, test, drug or device is needed to diagnose or treat a patient’s condition. It supports a request for approval or an appeal.
Who writes a medical necessity letter?
Usually the treating doctor or clinician writes and signs it. A patient can ask for one, and can bring a draft like the samples on this page for the doctor to edit.
What should a medical necessity letter include?
The patient’s name and member ID digits, the diagnosis, the history, what was tried, why the care meets accepted standards, the risk without it, one clear request and the doctor’s signature.
What does medically necessary mean?
HealthCare.gov defines it as services or supplies needed to diagnose or treat an illness, injury, condition, disease or its symptoms that meet accepted standards of medicine.
What is preauthorization?
Preauthorization, also called prior authorization, is an insurer’s decision that a service, drug or equipment is medically necessary. HealthCare.gov notes it does not guarantee coverage.
How long do I have to appeal a denial?
HealthCare.gov says you generally have 180 days (6 months) from the denial notice to file an internal appeal.
How fast is an appeal decided?
HealthCare.gov says standard appeals are decided within 30 days if care is not yet received and 60 days if it was. Urgent appeals are decided as quickly as the condition requires, no later than 4 business days.
What if the insurer still says no?
You can request an external review within 4 months. HealthCare.gov says the decision comes within 45 days, or 72 hours if expedited, and the insurer must accept it.
Can my doctor file the appeal for me?
Yes. HealthCare.gov says your doctor or someone else you choose can file the appeal if you sign the required form.
Does a letter guarantee approval?
No. The insurer decides. A specific, well-documented letter gives the reviewer what it needs to decide.
Conclusion
A strong medical necessity letter is specific, factual and signed by the treating doctor. Name the patient, state the history and what was tried, explain why the care is needed and make one clear request. Use the builder above to draft yours today and take it to your doctor.
Related Reading
- Medical excuse letter for school
- Explanation letter for leave without a medical certificate
- Resignation letter due to medical reasons
- To whom it may concern letter format
Sources: HealthCare.gov, Internal appeals, External review, Medically necessary and Preauthorization. The doctors, patients, plans and details are fictional.