When your health plan denies a claim, your first formal step is an internal appeal — you ask the insurer to review its own decision and explain why it was wrong. This general-purpose letter works for most denial reasons (coding, medical necessity, coverage, paperwork) and asks for a full review with your supporting evidence attached. For ACA-compliant plans, federal rules generally give you 180 days from the date of the denial to file an internal appeal. Always confirm the real deadline and the exact mailing address on your own denial letter or Explanation of Benefits (EOB), because those control.
Before you appeal
Gather these before you write so the letter is specific and complete:
- The denial letter or EOB showing the decision.
- The denial reason and code exactly as stated on that document.
- Your member ID, group number, and claim number.
- The date(s) of service and the date of the denial.
- Supporting records: a letter of medical necessity from your doctor, relevant medical records or test results, and any prior authorization or referral on file.
The letter
[Your full name]
[Your address]
[City, State ZIP]
[Phone] | [Email]
[Date]
[Insurance company - Appeals Department]
[Address from your denial letter]
Re: Internal appeal of denied claim
Member: [Name] Member ID: [number] Group #: [number]
Claim number: [number] Date(s) of service: [dates]
Denial date: [date] Denial reason/code: [as stated on the EOB]
To the Appeals Department:
I am requesting a full internal appeal of the denial of the claim identified
above. I have reviewed the stated reason for denial, and I believe the claim
should be paid for the following reasons:
[State plainly why the service should be covered. For example: the service was
medically necessary as documented by my treating physician; the denial appears
to be a coding or processing error; the service is a covered benefit under my
plan; prior authorization was obtained on [date]; or the information the plan
relied on was incomplete or incorrect.]
I am enclosing documentation that supports this appeal and addresses the
specific reason for the denial.
Enclosed in support:
- [Letter of medical necessity from Dr. [name]]
- [Relevant medical records / test results]
- [Copy of the EOB / denial letter]
- [Prior authorization or referral, if applicable]
Please conduct a full review and notify me of your decision in writing within
the timeframe required for my plan. If you uphold the denial, please send the
specific reason, identify the plan provisions and clinical criteria you relied
on, and tell me how to request an external review.
Thank you for your prompt attention.
Sincerely,
[Your signature]
[Your printed name]
How to send it
File within your plan’s deadline — often 180 days for ACA plans, but check your denial letter, since some plans and timely-filing situations differ. Send by certified mail with return receipt requested, or use the plan’s official appeals portal, fax, or address listed on the denial. Keep a dated copy of everything you send and any tracking or confirmation. If a delay could seriously harm your health, request an expedited (urgent) appeal instead, which is decided much faster.
Notes. Under federal ACA rules, internal-appeal decisions are generally due within about 30 days for services not yet received (pre-service) and about 60 days for services already received (post-service); urgent appeals are typically decided within about 72 hours. It helps to first read your denial letter carefully, and you can request your ERISA claim file to see exactly what the plan relied on. If your denial is based on medical necessity, see the medical-necessity appeal guide; if the internal appeal fails, you can usually escalate to an external review, which is binding on ACA plans. This is general information, not legal or medical advice.