A Letter of Medical Necessity (LMN) is required when an otherwise potentially eligible medical expense needs provider certification to confirm it is medically necessary, and reimbursement is only allowed if the LMN is complete, signed, dated, and covers the treatment period.
Without a valid LMN, these types of expenses will be denied for reimbursement.
What is a Letter of Medical Necessity (LMN)?
A Letter of Medical Necessity is a document from a licensed healthcare provider that confirms:
The patient has a specific medical condition or diagnosis
The recommended treatment or product is medically necessary
The treatment is intended to address the diagnosed condition
The expected duration of treatment
Provider certification (signature, credentials, and date)
The LMN is used to justify reimbursement for expenses that are not automatically eligible under IRS rules without additional documentation.
According to the Internal Revenue Service (IRS), some healthcare services and products are only eligible for reimbursement through your HRA when your doctor or provider certifies that they are medically necessary.
When is an LMN required?
An LMN is required when the expense is:
Not clearly eligible under IRS Section 213(d) without documentation
A product or service that requires medical justification
Commonly flagged for additional review due to non-standard usage
Typical categories that often require an LMN include:
Certain supplements or vitamins
Probiotics
Massage therapy
Orthopedic or corrective footwear (in non-standard cases)
Weight management medications or treatments (as required by plan rules)
Other wellness items where medical necessity must be established
If an expense is clearly eligible under IRS rules (e.g., standard prescription drugs), an LMN is typically not required.
What must be included in a valid LMN?
A valid LMN must include all of the following:
Patient identification
Name of the individual receiving treatment
Specific diagnosis
Must be precise and medically detailed (not general symptoms)
Example: “lumbar spinal stenosis with L3 disc herniation” instead of “back pain”
Treatment description
Exact product, service, or therapy being prescribed
Must clearly connect to the diagnosis
Medical necessity statement
Provider must explicitly certify that the treatment is medically necessary
Treatment duration
Must include clear start and end dates
Indefinite or lifetime durations are not accepted
Provider verification
Must be signed, dated, and include provider credentials
Must be on letterhead or clearly attributable to the provider
How long is an LMN valid?
An LMN is valid:
For up to 1 year from the provider’s signature date, unless a shorter duration is specified
Only for the treatment period explicitly listed in the letter
For a single plan year (a new LMN is required each plan year)
If treatment continues beyond the validity period:
A new LMN must be submitted
Continuation is not automatic
When do I need to submit an LMN?
You must submit an LMN:
With the first claim for the expense or treatment
When submitting reimbursement for a new product or service category requiring justification
At the start of each plan year if the expense continues
If an LMN is missing:
The claim will be placed on hold or denied
Reimbursement will not be processed until documentation is complete
Does an LMN guarantee reimbursement?
No.
Even with a valid LMN:
The expense must still qualify under IRS and plan rules
The LMN must meet all documentation requirements
The claim must be eligible under the employer’s HRA plan design
An LMN only confirms medical necessity—it does not override eligibility rules.
What happens if my LMN is incomplete?
An LMN may be rejected if:
Diagnosis is too vague
Treatment is not clearly defined
Dates of treatment are missing
Provider signature or credentials are missing
Document is undated or expired
If rejected:
You will be asked to submit a corrected LMN
The claim will remain unpaid until resolved
Do I need a new LMN every year?
Yes. A new LMN is required:
Every plan year
When treatment changes significantly
When the original LMN expires
LMNs cannot be used indefinitely across multiple years.
How do I submit an LMN?
Obtain the LMN from your licensed healthcare provider
Ensure it includes all required elements
Combine it with your receipt or claim documentation (if applicable)
Upload it through your Take Command Health portal with your expense submission
Submit for review