How to Write a Claim Appeal Letter: Step-by-Step Federal Requirements

How to Write a Claim Appeal Letter and Save Money

A claim denial is not final. You have a legal right to appeal—and according to federal regulations enforced by the Centers for Medicare & Medicaid Services (CMS), your insurance company must provide you with clear information about how to challenge their decision.

This guide provides step-by-step instructions for writing an effective appeal letter, based on guidance from HealthCare.gov, the Patient Advocate Foundation, and state insurance regulators.

Your Appeal Rights Under Federal Law

According to the HealthCare.gov internal appeals guide, you have two distinct options when your claim is denied:

1. Internal Appeal (Reconsideration) Your insurance company reviews its own decision. For standard appeals involving services already received, they have 60 days to respond. For urgent cases, they must review within 4 business days and provide verbal notification followed by written confirmation within 48 hours.

2. External Review An independent third party—not your insurance company—reviews the denial. This is available if the internal appeal is denied or if you want to bypass the internal appeal entirely.

Timeline: You have up to 180 days (6 months) from the date of the denial notice to file an appeal.

Common Reasons for Claim Denials

Understanding exactly why your claim was denied is essential to crafting a strong appeal. Review your denial letter for the specific reason, which typically falls into one of these categories:

1. Incorrect or Missing Patient Information: Name, date of birth, or policy number errors trigger automatic denials.
2. Lack of Medical Necessity: The insurer claims the treatment wasn't appropriate for your diagnosis.
3. Out-of-Network Provider: You received care from a provider outside your insurance network (note: the No Surprises Act protects you from surprise bills for emergency care).
4. Missing Documentation: Required medical records, test results, or provider notes were not submitted with the claim.
5. Not a Covered Service: The specific procedure or treatment falls outside your plan's coverage.
6. Pre-Authorization Not Obtained: Certain services require advance approval that wasn't received before care was delivered.

Essential Information to Include in Your Appeal Letter

According to the Patient Advocate Foundation, a strong appeal letter must include the following information:

1. Basic Information (Required by Federal Law)

Your appeal must clearly identify the claim:

• Your name and the policyholder's name (if different)
• Policy number and health insurance ID number
• Claim number (found on your denial letter)
• Date of denial letter
• Specific service or procedure denied (with date provided)
• Your contact information (phone, email, mailing address)

2. The Appeal Statement

Start with a clear, direct statement:

"I am requesting an appeal of your denial letter dated [DATE] regarding [SPECIFIC SERVICE]. I believe this denial was incorrect and respectfully request a full and fair review under federal regulations."

3. The Insurer's Stated Reason

Quote the specific reason your claim was denied (from your denial letter). This shows you understand their concern and can address it directly.

4. Your Medical Necessity Argument

This is the core of your appeal. Explain why you needed this treatment:

• Your diagnosis or medical condition
• Symptoms or health problems you experienced
• Why this specific treatment was appropriate for your condition
• What your doctor recommended and why

5. Policy Language and Coverage References

Quote relevant sections from your Evidence of Coverage or plan handbook that support coverage. For example:

"Page 45 of my Evidence of Coverage states that physical therapy is covered when 'medically necessary for treatment of a covered condition.' My condition clearly meets this standard."

6. Medical Support Documentation

The Patient Advocate Foundation emphasizes the importance of including:

• Letter from your treating physician explaining medical necessity
• Clinical evidence or research supporting the treatment (if available)
• Records of prior treatments you've tried
• Test results or diagnostic reports supporting the need for treatment
• Second opinions (if applicable)

7. Additional Documentation

Include copies (never originals) of:

• Your original denial letter
• Explanation of Benefits (EOB) showing the denial
• Medical records from your provider
• Lab results or imaging studies
• Any previous correspondence with the insurer

How to Submit Your Appeal

Format Options

Per the CMS appeal guidelines, you can submit your appeal:

• In writing (recommended for record-keeping)
• By phone (only for urgent cases)
• Using your insurer's required form (if they provide one)

Your insurer cannot require you to use their form if you choose to write a letter instead.

Submission Method

The Washington State Office of Insurance Commissioner recommends:

• Send by certified mail with return receipt (proof of delivery)
• Keep a copy for your records
• Address it to: The appeals analyst or appeals department name listed in your denial letter
• Allow 5-7 business days for delivery

Documentation Best Practices

Maintain a Contact Log (template available from state insurance commissioners):

• Date and time of each call
• Name and title of person you spoke with
• Summary of what was discussed
• Any commitments made by the insurer

Check Your Bill for Errors Before Appealing

Before you submit your appeal, it's worth checking whether your bill contains errors that could support your claim. Many denials are actually based on billing mistakes that, once corrected, can lead to coverage. Use our free bill checker tool to identify potential errors in under 60 seconds—no signup required.

Why this matters for appeals: If you discover billing errors during your appeal process, you can reference these specific errors in your appeal letter. Many denials occur because of incorrect billing codes, duplicate charges, or misclassification—issues that are actually easier to win appeals for than medical necessity disputes.

Timeline and Response Expectations

Based on federal regulations:

Standard Appeals (services already received):

• Insurer must respond within: 60 days
• You receive written explanation of their decision
• Includes instructions for external review if denied

Urgent Appeals:

• Insurer must respond within: 4 business days (verbally)
• Written confirmation: Within 48 hours

Your deadline to appeal:

• 180 days (6 months) from your denial notice

If Your Internal Appeal Is Denied

You have the right to request an external review. An independent organization not affiliated with your insurance company will reconsider the denial. Your denial letter explains how to request this, and there is typically no cost to you.

Skip the DIY Guesswork: Let CostKits Handle Your Appeals Professionally

Writing an effective appeal letter requires expertise in insurance policy language, medical coding, and federal appeals regulations that most families don't possess. CostKits' professional advocates create winning appeals using proven documentation and data that insurance companies take seriously.

What makes CostKits appeals successful:

✅ Policy-specific arguments based on your exact insurance contract terms ✅ Medical necessity documentation using clinical evidence and physician letters ✅ Federal compliance ensuring appeals meet all procedural requirements ✅ Professional documentation with organized, credible supporting materials ✅ Persistent follow-up ensuring your appeal is processed and tracked

Why DIY appeals often fail:

• Weak medical necessity arguments instead of clinical evidence
• Missing policy references from your Evidence of Coverage
• Incomplete documentation that insurance companies require
• Emotional language instead of data-driven arguments
• No follow-up after submission

Let our professionals handle your claim appeal →

CostKits Appeal Success Examples: Real Results from Professional Advocacy

Professional advocacy makes the difference between generic appeal attempts and successful claim reversals. Here are recent CostKits wins that show what's possible with expert representation:

1. Complex Surgery Pre-Authorization Appeals

• Challenge: Surgery denied as "experimental"
• CostKits Strategy: Locate peer-reviewed studies and FDA approvals supporting medical necessity
• Potential Result: Full approval with proper documentation

2. Mental Health Coverage Appeals

• Challenge: Therapy sessions denied as "not medically necessary"
• CostKits Strategy: Compile clinical documentation meeting specific policy criteria for coverage
• Potential Result: Complete reversal with retroactive payment

3. Out-of-Network Emergency Care Appeals

• Challenge: Emergency surgery denied as "out-of-network choice"
• CostKits Strategy: Demonstrate no in-network emergency options were available within required time
• Potential Result: Full coverage approved as in-network equivalent

The key difference: CostKits appeals include specific policy language, clinical evidence, and regulatory requirements that DIY appeals typically miss.

Tips for a Successful Appeal

Insurance Claim Tips

• Follow Up: After sending your appeal, follow up with the insurance company to ensure it’s being processed.
• Keep Records: Maintain a detailed record of all communications regarding your claim.
• Be Persistent: If your first appeal is denied, don’t hesitate to appeal again with additional information.

Healthcare Invoice Check

Conducting a thorough healthcare invoice check can help identify errors before they lead to denials. Look for:

• Duplicate charges
• Incorrect service dates
• Services not covered by your plan

Frequently Asked Questions About Claim Appeals

What should I do immediately after receiving a claim denial?

1. Read the entire denial letter carefully to find the specific reason for the denial
2. Write down the key information: claim number, denial date, and stated reason
3. Contact your doctor's office to request medical records and ask if they'll provide a letter of medical necessity
4. Get a copy of your Evidence of Coverage (your insurance plan rules)
5. Mark your calendar with the 180-day deadline to appeal

How long do I have to appeal?

You have up to 180 days (6 months) from the date of the denial letter to file your appeal. Don't wait—submit your appeal as soon as you have your supporting documentation ready.

What happens if I miss the 180-day deadline?

Once 180 days pass, most insurance companies will not accept an appeal. If you've missed the deadline, contact your state's insurance commissioner's office for assistance, as they may have additional remedies available.

Can I appeal a claim denial more than once?

Yes. You can file an internal appeal first. If that's denied, you can request an external review by an independent third party. If external review is denied, some state insurance commissioners offer additional appeals processes.

What if my insurer says I can't appeal without a specific form?

Federal law allows you to appeal by writing a letter instead. According to the CMS guidelines, your insurer cannot force you to use their form. A well-organized letter works just as well.

Should I call the insurance company or write a letter?

Write a letter by certified mail. This creates a record of your appeal and gives you proof of delivery. Phone calls are harder to document and easier for the insurer to overlook. Reserve phone calls for collecting information, then follow up in writing.

Who can help me write my appeal letter?

You can write it yourself, but these people can also help:

• Your doctor (often provides the strongest medical necessity argument)
• A patient advocate (many hospitals have patient advocates on staff—ask)
• Your state's insurance commissioner (provides free templates and guidance)
• Professional advocates or attorneys specializing in insurance appeals

What if I don't have medical records?

Request them from your doctor's office immediately. Provide:

• Your full name and date of birth
• The date(s) of service in question
• Type of records needed (office notes, test results, etc.)

By law, doctors must provide records within 30 days. If you're appealing an urgent matter, ask them to expedite.

Should I check my medical bill for errors before appealing?

Yes! Many claim denials are actually triggered by billing errors—duplicate charges, incorrect CPT codes, or misclassification. Before spending energy on a medical necessity appeal, use our free bill checker tool (embedded in this article) to identify if the underlying bill contains errors. If errors exist, addressing those often resolves the denial more quickly than appealing the original denial reason.

Do I need a lawyer to appeal?

Most people don't need a lawyer for internal appeals. If you do need help, the Patient Advocate Foundation and your state's insurance commissioner offer free guidance first.

What should I do if the internal appeal is denied?

Request an external review by an independent organization. The insurer's denial letter explains how to request this. There is typically no cost to you, and the independent reviewer may rule in your favor even if the insurer's appeal was denied.

Stop Struggling with DIY Appeals: Get Professional Results

While understanding appeal basics is valuable, the reality is that successful claim appeals require specialized expertise in insurance law, medical coding, and regulatory procedures. Insurance companies rely on most families giving up after the first denial—that's why 64% of DIY appeals fail.

CostKits transforms claim appeals from guesswork to guaranteed results:

✅ High appeal success rate compared to DIY approaches
✅ Meaningful recoveries often achieved for successful appeals
✅ Professional documentation that insurance companies take seriously
✅ Regulatory compliance ensuring appeals meet all procedural requirements
✅ No upfront costs - we only get paid when you save money

CostKits families often recover significant amounts annually through successful claim appeals and bill negotiations. Instead of spending hours learning insurance policy language and appeal procedures, let our professionals handle the complex work while you focus on your family's health.

Don't let insurance companies keep your money.

Sign up free → https://app.costkits.com/signin/ (magic link; no card required)

Upload your claim denial today and see what our appeal specialists can recover for your family.

Related Articles

Learn more about protecting yourself from billing errors, disputes, and insurance coverage issues:

• How to Fight Medical Bill Errors: The Complete Dispute Toolkit – Discover the 4 most common billing errors (duplicate charges, preventive care misclassification, balance billing, upcoding) and how to dispute them with real examples and templates.

• How to Negotiate Your Medical Bills: A Patient's Playbook – Learn professional negotiation strategies, how to identify financial assistance programs, and why DIY negotiations often fail.

• How to Read Your Medical Bill: A Step-by-Step Guide for Families – Master the basics of medical billing by understanding CPT codes, modifiers, and how to verify charges before they become appeal disputes.

External Resources & References

This article is based on guidance from authoritative government and nonprofit sources:

• HealthCare.gov: Appeal an Insurance Company Decision – Official federal guide to your internal and external appeal rights
• HealthCare.gov: Internal Appeals – Detailed requirements and timelines for federal appeals
• CMS Fact Sheet: How to Appeal a Denied Claim – Official Centers for Medicare & Medicaid Services guidance
• Patient Advocate Foundation: Things to Include in Your Appeal Letter – Nonprofit expert guidance on appeal letter components
• Patient Advocate Foundation: Sample Appeal Letter – Download an actual example you can adapt
• NAIC: How to Appeal a Denied Claim – State insurance regulators' guide to the appeals process
• Washington State Office of Insurance Commissioner: How to Appeal – Templates and step-by-step instructions from state regulators
• No Surprises Act – Federal protections against surprise billing for emergency care

All information in this article reflects federal requirements under the Affordable Care Act and state insurance regulations current as of January 2026.