Universal elements every appeal needs
Before you copy a template, know what every appeal letter must contain regardless of denial type:
- Identifying header: your full name, date of birth, member ID, group number, claim number, date of service, provider name and NPI.
- Reference to the specific denial: quote the denial reason from the letter and its CARC code (e.g., "CO-50: not medically necessary"). Decode your CARC here.
- The clinical rebuttal: physician's clinical reasoning, ICD-10 diagnoses, conservative-therapy failures, imaging/lab evidence.
- The regulatory anchor: the federal law, state law, or plan provision that supports your position (ACA, ERISA, MHPAEA, No Surprises Act).
- The procedural ask: what you want the insurer to do (overturn, expedite, schedule peer-to-peer, refer to external review).
- Documentation appendix: chart notes, imaging reports, lab results, letter of medical necessity from your physician, prior appeal correspondence.
- Signature block: your signature, date, and contact information; cc your physician and a copy to your state Department of Insurance if you've already lost the first round.
Most appealable · ~44% overturn rate
1. Medical Necessity Denial (CO-50)
When to use: the denial letter says some variation of "not medically necessary," "does not meet medical necessity criteria," or "experimental for this indication" with code CO-50.
Win condition: the medical reviewer needs to see clinical evidence that your specific case meets the criteria they applied. Generic appeals lose. Specific clinical narrative wins.
Framework:
[Your Name]
[Address]
[Date]
[Insurer Name — Appeals Department]
[Address from denial letter]
Re: Appeal of denial dated [date]
Member: [Your Name] ID: [member ID]
Claim #: [claim #] DOS: [date of service]
Provider: [name, NPI] Denial code: CO-50
To Whom It May Concern:
I am appealing the denial of [procedure/service] performed on [date]. The
denial cites code CO-50 and states the service was "not medically necessary."
This appeal demonstrates the service was, in fact, medically necessary for
my specific clinical presentation.
Clinical history: I have been diagnosed with [ICD-10 diagnosis and code]
since [date]. My treating physician, Dr. [Name], has documented the following
clinical findings: [chart-note bullet 1]; [chart-note bullet 2]; [imaging
or lab result with date and finding].
Conservative therapy: Prior to [procedure], I attempted [therapy A] for
[duration], followed by [therapy B] for [duration]. Both were inadequate
to control [symptoms], as documented in the attached chart notes.
Standard of care: The requested service is consistent with [specialty
society / clinical guideline / NCD-LCD reference]. The attached letter of
medical necessity from Dr. [Name] cites [specific guideline section] and
explains why the procedure is the standard-of-care intervention for my
presentation.
Procedural request: I request that this denial be overturned and the
claim paid. If your medical reviewer concludes additional information is
needed, I request a peer-to-peer review between Dr. [Name] and your
medical director before any further decision is issued.
Attached: chart notes ([dates]), imaging reports ([dates]), lab results,
letter of medical necessity from Dr. [Name] dated [date].
Sincerely,
[Signature]
[Printed name]
[Phone, email]
cc: Dr. [Name]
See also: Full CO-50 appeal deep-dive · Medical-necessity rights guide
Often overturned
2. Prior Authorization Missing (CO-197 / CO-198)
When to use: denial cites missing pre-authorization, pre-certification, or pre-notification. Strongest if the service was urgent or emergent.
Framework:
Re: Appeal of denial dated [date] — CO-197 prior authorization absent
Member: [name] ID: [member ID] Claim #: [claim #] DOS: [date]
I am appealing the denial of [procedure] on [date]. The denial cites
CO-197 (precertification absent).
Urgency / emergency basis: The procedure was performed [under what
circumstances — e.g., during an ER visit, urgent same-day surgical
indication, post-hospitalization complication]. Under 29 CFR
§2590.715-2719A and my plan's emergency-services provisions, the plan
cannot deny payment for emergency services based on prior-authorization
requirements that could not reasonably have been met before care was
delivered.
OR (if non-emergent):
Retrospective authorization request: I respectfully request a
retrospective authorization for the [date] service. Attached is clinical
documentation showing the procedure met the criteria that would have
been required for prospective approval, including [diagnosis, conservative
therapy history, imaging].
I respectfully request the denial be overturned. If retrospective
authorization is not granted administratively, please schedule a
peer-to-peer review with Dr. [Name].
See also: Full prior-auth appeal guide
3. Experimental / Investigational (CO-96)
When to use: insurer denies as "experimental," "investigational," or "not generally accepted." Common for newer cancer therapies, gene therapies, off-label drugs.
Framework:
Re: Appeal of denial — service classified as experimental/investigational
Member: [name] ID: [member ID] Claim #: [claim #]
The denial states [procedure/medication] is experimental or investigational
for my condition. This is incorrect because:
1. FDA status: [Drug/device] received FDA approval/clearance on [date]
for [indication]. The use in my case is an FDA-approved indication
(or an FDA-recognized off-label use supported by compendia listed at
42 CFR §414.930).
2. Standard-of-care evidence: [NCCN, ASCO, specialty society] guidelines
(version [X], [year]) recommend [therapy] for my specific presentation
([diagnosis, stage, line of therapy]). Citation: [specific guideline
section and DOI].
3. Peer-reviewed evidence: [Cite 2-3 peer-reviewed studies with PMIDs
supporting the therapy for this indication, including the highest
level-of-evidence study available].
4. State mandate (if applicable): [State law / state insurance mandate
requiring coverage of FDA-approved cancer therapies, for example].
I request the denial be overturned and the claim paid at the in-network
benefit level.
4. Out-of-Network Emergency (PR-242)
When to use: emergency room visit at an out-of-network facility, or an in-network facility with out-of-network ER physicians/radiologists/anesthesiologists. Federal No Surprises Act protects you here.
Framework:
Re: Appeal — No Surprises Act protection applies
Member: [name] ID: [member ID] Claim #: [claim #] DOS: [date]
The denial / cost-sharing on this claim does not comply with the federal
No Surprises Act (NSA) (P.L. 116-260, codified at 45 CFR Part 149).
Facts: On [date], I [presented to / was admitted to] [facility] for
[chief complaint]. The presenting symptoms (chest pain, severe abdominal
pain, etc.) would lead a "prudent layperson" to believe immediate medical
attention was required to avoid serious health consequences — the
standard adopted in 42 USC §1395dd(e) and incorporated into NSA.
Therefore:
1. Cost-sharing must be calculated as if the service were in-network
(NSA §102(a)(1)). The full out-of-network deductible and coinsurance
billed are incorrect.
2. Any balance bill from an out-of-network emergency provider is
prohibited under NSA §102(b). If I have received such a bill, that
amount should be removed.
3. If the facility was in-network but the rendering provider (ER
physician, anesthesiologist, radiologist) was out-of-network, NSA
§103 covers it — same in-network cost-sharing applies.
I request the claim be reprocessed with in-network cost-sharing and any
balance-bill amounts removed.
5. Diagnosis Not Covered (CO-167)
When to use: insurer says the diagnosis code on the claim isn't on their covered-indication list for the billed procedure.
Framework:
Re: Appeal of CO-167 diagnosis-not-covered denial
Member: [name] ID: [member ID] Claim #: [claim #]
The denial states the diagnosis on this claim is not covered for the
procedure billed. I respectfully appeal on two grounds:
1. Coding correction: My medical record supports the more specific
diagnosis code [ICD-10 code and description], which is on your medical
policy's covered list for this procedure. I have requested my provider
resubmit with the corrected code.
2. Policy applicability: Even with the original diagnosis, this procedure
is standard of care per [guideline reference and year]. Your medical
policy [number, version] was last updated [date]; the standard of care
has evolved since then to include the indication in my case, as
documented in [study/PMID].
I request review by a medical director with [relevant specialty] training.
6. Coding / Bundling Dispute (CO-97)
When to use: insurer says the service is bundled into another procedure already paid. NCCI edits are often misapplied.
Framework:
Re: Appeal of CO-97 bundling denial
Member: [name] ID: [member ID] Claim #: [claim #]
The denial states [procedure A] is bundled into payment for [procedure B].
This is incorrect because the two services were distinct:
[Choose applicable basis:]
1. Different anatomical sites: [Procedure A] was performed on [site 1]
and [procedure B] on [site 2]. Modifier -59 (distinct procedural service)
applies; provider should resubmit with -59.
2. Separate sessions: [Procedure A] was performed at [time/date 1] and
[procedure B] at [time/date 2]. Operative notes attached show timestamps.
3. NCCI edit misapplication: The current CMS NCCI manual (chapter [X],
table [Y]) lists these CPT codes as eligible for separate payment when
appropriate modifiers are used. See attached page.
I request the claim be reprocessed with the appropriate modifier and
payment issued for [procedure A].
7. Timely Filing (CO-29)
When to use: claim denied as past the filing deadline. Hard to win but possible with proof of timely submission or a good-cause exception.
Framework:
Re: Appeal of CO-29 timely-filing denial
Member: [name] ID: [member ID] Claim #: [claim #] DOS: [date]
[Choose applicable basis:]
1. Proof of timely submission: This claim was originally submitted on
[date], within your [X-day] filing window. Attached: EDI submission
confirmation, payer rejection letter, or claim acknowledgement showing
the original timely submission.
2. Good-cause exception: My claim was delayed because [valid reason —
COB resolution between primary/secondary payers, retroactive enrollment,
the insurer's own prior error]. Under [plan's good-cause provision /
ERISA tolling principle], the filing clock should be tolled for the
period [X] to [Y].
3. Retroactive Medicaid/Medicare eligibility: My eligibility was
established retroactive to [date]; the filing clock for retroactively
covered services begins at the eligibility determination date.
I request the denial be overturned and the claim processed on its merits.
8. Drug Formulary Exception (PR-204 / non-formulary)
When to use: pharmacy denial says the drug isn't covered or is off-formulary. Most plans have a separate "exception" process — faster than full appeal.
Framework:
Re: Formulary exception request — [drug name + strength]
Member: [name] ID: [member ID] Prescriber: Dr. [name, NPI]
I am requesting a formulary exception for [drug] for treatment of [ICD-10
diagnosis]. The formulary alternatives are inappropriate because:
1. [Alternative drug A]: contraindicated due to [allergic reaction /
adverse event / drug interaction with my current regimen].
2. [Alternative drug B]: previously trialed for [duration]; produced
[side effect / lack of efficacy as documented in chart].
3. [Alternative drug C]: would result in interruption of stable
therapeutic response on the requested drug, with documented prior
exacerbations on alternatives.
Attached: physician letter of medical necessity, prior trial documentation,
and current clinical notes.
I request urgent processing if my supply is exhausting within [X] days.
9. Mental Health Parity (CO-119 visit cap)
When to use: behavioral-health or substance-use claim denied for visit-count, day-count, or session-count limit. Federal Mental Health Parity and Addiction Equity Act (MHPAEA) likely applies.
Framework:
Re: MHPAEA parity violation — visit limit appeal
Member: [name] ID: [member ID] Claim #: [claim #]
The denial cites a [X]-visit annual cap for [mental health / SUD] services.
This violates the Mental Health Parity and Addiction Equity Act of 2008
(MHPAEA), 29 USC §1185a, as integrated into the ACA at 42 USC §300gg-26.
MHPAEA requires that quantitative treatment limitations (visit caps,
session limits, day limits) on mental health and substance use disorder
benefits be no more restrictive than the predominant limitations applied
to substantially all medical/surgical benefits.
Comparator: Your plan applies [no visit limit / a higher visit limit /
unlimited visits] to comparable medical/surgical benefits (e.g.,
physical therapy, cardiac rehabilitation, chronic disease management).
A [X]-visit cap on behavioral health while M/S has [higher/no] cap is a
parity violation.
I request the denial be overturned and parity-compliant coverage applied.
I am also requesting your plan's NQTL comparative analysis under
MHPAEA §512(a) if the limit is being justified on non-quantitative grounds.
I am providing a copy of this appeal to my state Department of Insurance
and to the federal Department of Labor / HHS, as MHPAEA enforcement is
shared.
Use after internal appeal denied
10. External Review Request
When to use: your internal appeal was denied (or insurer didn't meet decision deadlines). External review by an Independent Review Organization (IRO) is binding on the insurer if it rules in your favor.
Framework:
Re: Request for External Review under ACA §2719(b)
Member: [name] ID: [member ID] Original claim #: [claim #]
I am requesting external review of the final internal denial dated [date]
for [procedure / service]. This request is timely under the federal
4-month window from final internal denial.
This appeal is eligible for external review because:
- The denial involves a medical-judgment decision (e.g., medical necessity,
experimental/investigational, level-of-care) — not solely a contractual
exclusion.
- I have exhausted the insurer's required internal appeal process (or the
insurer failed to issue a final decision within the regulatory timeframe).
I request:
- An expedited external review under ACA §2719(b)(2)(B) because [delay
would jeopardize life/health/function] (OMIT if standard timeline OK).
- Independent Review Organization randomly assigned per the URAC-accredited
process; I have no preference among IROs.
Attached: original denial letter, all internal-appeal correspondence,
clinical chart notes, letter of medical necessity, and the specific medical
policy or plan language at issue.
These are starting frameworks — not finished letters.
A finished letter cites your exact diagnoses, your specific conservative-therapy timeline, the precise clinical-policy section the insurer applied, and the regulatory anchor that overrides their position. ClaimCure's $49 service generates that finished letter from your actual denial in 24 hours:
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