Insurance Appeal Letter: Free Templates for a Denied Claim

Most denied claims are never appealed. KFF’s 2026 analysis of CMS transparency data found that HealthCare.gov insurers denied 19% of in-network claims in 2024 and that consumers appealed fewer than 1% of those denials. Of the appeals that were filed, insurers upheld 66%, which means roughly one in three got reversed by the same company that issued the denial.

The letter is the whole job. A phone call leaves no record and starts no clock. A written appeal creates a dated document the plan must respond to on a federal timetable, and it becomes the record an independent external reviewer reads later if you need one. This page gives you the required elements and two letters you can copy. For the full procedure, deadlines by plan type, and where to escalate, see how to appeal a health insurance denial.

Step 1: Collect the 7 Elements Every Appeal Letter Needs

Do not start writing until you have all seven. Six of them are on the denial notice or your explanation of benefits.

1. Member ID and group number. Exactly as printed on your card.
2. Claim number and date of service. Plus the provider name and, if you have it, the NPI. Without the claim number the letter can sit unmatched for weeks.
3. The denial reason, quoted verbatim. Copy the sentence and the denial code from the notice. Quoting it back forces the reviewer to address that reason specifically instead of restating a generic policy.
4. The rule the plan applied. Under 29 CFR 2560.503-1, the plan must give you, free of charge on request, copies of everything relevant to your claim, plus the internal rule or clinical criterion it relied on and, for a medical-necessity or experimental denial, the clinical explanation applied to your circumstances. Request it before or with your appeal, and name it in the letter.
5. Your counter-argument. Either the plan’s own document does not say what the denial says it says, or your situation meets the clinical criteria the plan used. Pick one and stay on it.
6. The specific relief you want. “Reverse the denial of claim 123456 and pay the claim at the in-network benefit level” beats “please reconsider.”
7. The deadline you are filing within. State that you are filing inside the 180-day window under 29 CFR 2560.503-1(h)(3). It signals you know the rule.

Keep the letter to one page. The evidence goes in the attachments.

Step 2: Copy the Standard Internal Appeal Letter

Use this for a medical-necessity, experimental, or coverage denial where the care is not urgent. Replace everything in brackets.

[Your name]
[Street address, city, state, ZIP]
[Phone]  [Email]
[Date]

[Insurer name] - Appeals Department
[Address from the denial notice]

RE: FORMAL INTERNAL APPEAL OF ADVERSE BENEFIT DETERMINATION
Member name: [Name]      Member ID: [ID]      Group #: [Group]
Patient name: [Name]     Date of birth: [DOB]
Claim number: [Claim #]  Date(s) of service: [Date]
Provider: [Provider name and NPI]
Denial notice dated: [Date on the letter]

To the Appeals Department:

I am filing a formal internal appeal of the adverse benefit
determination dated [date] denying coverage for [service, drug,
or procedure, with CPT/HCPCS or NDC code if known]. I am filing
within the 180-day period required by 29 CFR 2560.503-1(h)(3).

1. THE DENIAL AS STATED
Your notice gives this reason: "[paste the exact sentence and
denial code from the notice]."

2. WHY THAT REASON DOES NOT APPLY
[Two to five sentences. Use ONE of these lines of argument:
 - Plan language: the certificate of coverage / Summary Plan
   Description at [section, page] covers [service] and does not
   list the exclusion cited. Quote the plan text.
 - Clinical criteria: the criteria you applied, [name the
   criteria set], require [criterion]. The attached records show
   [finding], [prior therapies tried and failed], and [dates],
   which meet that criterion.
 - Administrative: the claim was submitted with [correct code /
   referral / authorization number], attached, so the stated
   basis for denial is factually inaccurate.]

3. RECORDS AND CRITERIA REQUESTED
Under 29 CFR 2560.503-1(h)(2)(iii) and (g)(1)(v), please provide
free of charge: the complete claim file; the specific internal
rule, guideline, protocol, or clinical criterion relied upon; the
explanation of the scientific or clinical judgment applied to my
circumstances; and the credentials of the reviewer and of any
medical expert consulted. Please confirm that the reviewer of
this appeal was not involved in the original determination.

4. RELIEF REQUESTED
Reverse the denial and process claim [number] for payment at the
[in-network / applicable] benefit level.

5. ENCLOSURES
[List them: denial notice, EOB, letter of medical necessity,
office and chart notes, test results, prior authorization
record, cited plan pages.]

Please send your written determination to the address above
within the timeframe required by 29 CFR 2560.503-1(i)(2), and
include external review instructions if the denial is upheld.

Sincerely,
[Signature]
[Printed name]      [Date]

Step 3: Copy the Expedited (Urgent) Appeal Letter

Use this when waiting for a standard decision would seriously jeopardize your life, your health, or your ability to regain maximum function, or when you are already in treatment and a course of care is being cut off. An expedited appeal must be decided within 72 hours, a request for one can be made orally or in writing, and a physician who knows your condition can act as your authorized representative without any extra paperwork.

[Your name] | [Phone] | [Email] | [Date]

[Insurer name] - Appeals Department
Fax: [fax from the denial notice]     Phone: [appeals phone]

RE: REQUEST FOR EXPEDITED APPEAL AND SIMULTANEOUS EXPEDITED
    EXTERNAL REVIEW - 72-HOUR DECISION REQUIRED
Member: [Name]   Member ID: [ID]   Group #: [Group]
Patient: [Name]  DOB: [DOB]
Claim/authorization number: [Number]
Service denied: [Service or drug, with code]
Denial notice dated: [Date]

To the Appeals Department:

This is a request for an EXPEDITED internal appeal of the denial
dated [date]. The standard timeframe would seriously jeopardize
[my life / my health / my ability to regain maximum function]
because [one or two sentences: the clinical situation and the
time factor, e.g. treatment is scheduled for (date), or an
ongoing course of treatment is being terminated on (date)].

[Treating clinician name], [credentials], of [practice], phone
[number], is acting as my authorized representative and has
certified the urgency. The attached letter of medical necessity
is dated [date].

Under 29 CFR 2560.503-1(i)(2)(i), a determination on an urgent
care appeal is due as soon as possible and no later than 72 hours
after you receive this request. Please transmit the decision by
telephone and fax to the numbers above and follow with written
notice.

I am also requesting an EXPEDITED EXTERNAL REVIEW to run
concurrently with this internal appeal, as permitted for urgent
care claims. If your plan uses the HHS-administered federal
process, please forward this request accordingly and confirm in
writing.

RELIEF REQUESTED: Approve [service/drug] and authorize the
provider to proceed without delay.

ENCLOSURES: denial notice; letter of medical necessity; chart
notes; scheduling documentation.

[Signature]
[Printed name]   [Date]   [Phone reachable 24/7: number]

Step 4: Attach the Right Evidence

The letter frames the argument. The attachments win it. Send copies, never originals.

• The denial notice and the EOB. Proof of what was denied and when.
• The claim file and criteria the plan sent you, if it already responded to your records request. Otherwise, the request in section 3 preserves the issue.
• A letter of medical necessity from the treating provider. For a medical-judgment denial this matters most, because the plan is required to have a qualified clinician review the appeal. Ask the office for a letter naming the diagnosis codes, the therapies already tried and their outcomes, and why the denied service is appropriate now.
• Chart notes, imaging, and lab results that show the specific findings your argument depends on.
• The prior authorization record if the denial claims none existed. See prior authorization.
• The plan pages you quoted, highlighted.
• The formulary page for a drug denial, plus the plan’s exception form. Our drug formulary guide explains tiers and exception routes.

Step 5: Send It So You Can Prove You Sent It

Use the address, fax number, or portal named in the denial notice, not the general customer service address. Then create a delivery record: certified mail with return receipt, a fax confirmation page, or a portal screenshot showing the submission timestamp. Decision clocks run from receipt, so the receipt is the leverage.

Log the date sent, the method, the tracking or confirmation number, and every phone call afterward with the representative’s name and what they said. If you are appealing on someone else’s behalf, most plans need a signed authorized representative form first, with one exception: for an urgent care claim, a clinician with knowledge of your condition can act as your representative automatically.

Plans may not charge you anything to file a claim or an appeal.

Step 6: Know the Clock You Just Started

Once the plan has your letter, the federal deadlines apply.

Type of appeal	Decision due
Urgent care	72 hours
Pre-service (prior authorization)	30 days, or 15 days per level if the plan uses two levels
Post-service (care already received)	60 days, or 30 days per level if the plan uses two levels
External review, standard	45 days after the request is received
External review, expedited	72 hours

If the appeal is upheld, the final notice must tell you how to request an external review. You get 4 months from that final denial to file, the reviewer’s decision binds the plan, and the cost is either nothing (HHS-administered federal process) or capped at $25.

While the appeal runs, work the bill in parallel: ask the provider for the self-pay or prompt-pay cash price, apply for hospital charity care, and use the negotiation script if you need to hold collections off. Medicare denials follow a different track entirely, covered in our Medicare appeal guide.

The Bottom Line

Appeal letters do not win on tone. They win by naming the claim, quoting the denial back, attacking the one rule the plan actually applied, and asking for a specific outcome inside the 180-day window. Send it with proof of delivery, attach a letter of medical necessity for anything involving medical judgment, and calendar the 72-hour, 30-day, or 60-day clock the moment it lands. If the plan still says no, the independent reviewer is a better audience anyway.