The Step-by-Step Internal Appeal Process: What Happens After You File

You opened the mail and there it was. A denial letter from your insurance company. Maybe it was for a medication your doctor prescribed. Maybe a procedure you already scheduled. Either way, the message was clear: "We won't pay for this."

Here's what that letter probably didn't make clear: you have the right to fight back. Every insurance denial can be appealed, and the internal appeal process is your first and most important opportunity to get that decision reversed. This guide walks you through every step, from the moment you receive a denial to the moment you get a final answer.

What Is an Internal Appeal?

An internal appeal is a formal request asking your insurance company to review a denied claim again. The key word there is "again." Under federal law, the person reviewing your appeal must be different from the person who made the original denial decision. That's not a courtesy. It's a requirement.

The Affordable Care Act (ACA) requires all non-grandfathered health plans to provide at least one level of internal appeal. This means that regardless of whether your plan is through your employer, the marketplace, or purchased individually, you have this right built into your coverage.

And here's something that might surprise you: according to KFF data, 44% of internal appeals succeeded in 2023. Nearly half. Yet only about 1% of denied claims were actually appealed. That means tens of thousands of people accepted a "no" that could have been a "yes" simply because they didn't know they could push back, or didn't know how.

This guide is here to change that.

Before You Start: Know Your Deadline

The clock starts ticking the moment you receive your denial. Under ACA and ERISA standards, you generally have 180 days from the date you receive a denial notice to file an internal appeal. That's roughly six months. It sounds like a lot of time, but don't let it lull you into waiting.

The sooner you file, the sooner you get a decision. And if your appeal is denied, you'll still need time to pursue an external review. Start as soon as you can.

Step 1: Read Your Denial Letter Carefully

Your denial letter (also called an Explanation of Benefits, or EOB) is the single most important document in your appeal. It contains the specific reason your claim was denied, and that reason determines your entire strategy.

Look for the exact denial code or reason. Common ones include "not medically necessary," "experimental or investigational," "out of network," "prior authorization not obtained," or "step therapy requirements not met." Write it down. You'll reference this specific language in your appeal letter.

You also have the right to request your complete claim file and all documents relevant to the denial. This is your right under federal law, and insurers must comply. Call the number on your denial letter and ask for everything: the reviewer's notes, the criteria they used, any clinical guidelines they referenced. This information helps you understand exactly what went wrong and how to address it.

Step 2: Gather Your Documentation

A strong appeal is built on evidence. The more relevant documentation you include, the harder it is for a reviewer to say no a second time. Here's what you need to collect:

• •Your denial letter or Explanation of Benefits (EOB), which is the document you're responding to
• •Medical records that support the treatment, including diagnosis history, test results, and prior treatments
• •A letter of medical necessity from your treating physician explaining why this specific treatment is needed for your condition
• •Relevant clinical guidelines or peer-reviewed studies that support your doctor's recommended treatment
• •Your insurance plan's specific coverage criteria for the treatment or medication in question

The letter of medical necessity from your doctor is often the most persuasive piece of evidence. It should be specific to your situation, not a generic template. Your doctor should explain what they've tried, why alternatives won't work for you, and what the clinical consequences would be if treatment is delayed or denied.

Step 3: Write Your Appeal Letter

Your appeal letter is the centerpiece of your submission. It needs to be clear, organized, and focused on facts. You're not writing an emotional plea (though it's understandable if you feel emotional about it). You're building a logical case for why the denial was incorrect.

What to Include

• •Your name, date of birth, policy number, and contact information
• •The claim number or reference number from the denial letter
• •The specific reason for denial, quoted directly from the EOB
• •A clear statement of why the denial should be overturned
• •A summary of supporting evidence (medical records, physician letter, clinical guidelines)
• •A specific request for action. For example, "I am requesting that [treatment/medication] be approved and covered under my plan"

Writing Tips

Keep your tone professional and factual. Reference the denial reason by name and address it directly. If the denial says "not medically necessary," explain exactly why it is medically necessary for your specific situation. If the denial cites "step therapy requirements," document the alternative treatments you've already tried and why they failed.

Organize your letter so the most important information comes first. Reviewers process many appeals. Make it easy for them to find your key arguments. Number your supporting documents and reference them in your letter (e.g., "See Attachment 3: Letter of Medical Necessity from Dr. Smith").

If writing the appeal letter feels overwhelming, you're not alone. Tools like Appealio can help you draft and organize your appeal, but you can absolutely do this on your own with the information above.

Step 4: Submit Your Appeal

How you submit matters almost as much as what you submit. Your goal is to create an indisputable paper trail that proves your appeal was received on time.

The gold standard is certified mail with return receipt requested. This gives you a tracking number and a signed receipt proving the insurance company received your appeal on a specific date. Many plans also accept fax submissions, and an increasing number allow electronic submission through their member portals.

Whichever method you use, keep copies of everything. Every page you send, every receipt you get, every confirmation number. If you submit by fax, keep the fax confirmation sheet. If you submit online, take a screenshot with a timestamp. If a dispute arises later about whether your appeal was received, these records protect you.

Step 5: What Happens During the Review

Once your appeal is received, the insurance company assigns it to a reviewer who was not involved in the original denial decision. This reviewer examines your appeal letter, your supporting documentation, your medical records, and the plan's coverage criteria.

During the review period, you should know the timelines the insurer is required to follow under the ACA:

• •Pre-service claims (before treatment): The insurer must decide within 30 days
• •Post-service claims (treatment already received): The insurer must decide within 60 days
• •Urgent or expedited appeals (serious health risk from delay): The insurer must decide within 72 hours

If your situation is urgent, meaning a delay could seriously jeopardize your health, your ability to function, or could result in severe pain, ask for an expedited review. Your doctor can help make the case that your appeal qualifies as urgent.

While you wait, keep a log. Note when you submitted the appeal, when the insurer acknowledged receipt, and when the decision deadline falls. If the deadline passes without a decision, follow up. Silence is not an answer, and you have the right to know the status.

Step 6: The Decision

The insurance company will notify you of their decision in writing. There are two possible outcomes.

If Your Appeal Is Approved

The insurer will process the claim for payment. Depending on your plan, this might mean direct coverage for a future treatment, or reimbursement for a treatment you already paid for out of pocket. Review the approval letter carefully to make sure the coverage matches what you requested. If something looks off, call the number on the letter and clarify before proceeding.

If Your Appeal Is Denied

A denial is not the end. It's the end of one step. If your internal appeal is denied, you have the right to request an external review by an Independent Review Organization (IRO). This is a third-party entity that has no affiliation with your insurance company. They review the case independently, and here's the critical part: external review decisions are binding on the insurer. If the IRO says the treatment should be covered, your insurance company must comply.

Your denial letter from the internal appeal should include instructions on how to request an external review and the deadline for doing so. Read it carefully and act promptly.

Common Mistakes That Weaken Your Appeal

Even strong cases can be undermined by avoidable errors. Watch out for these:

• •Missing the 180-day filing deadline. This alone can disqualify your appeal entirely
• •Submitting without a letter of medical necessity from your treating physician
• •Writing a vague or emotional appeal letter instead of addressing the specific denial reason
• •Failing to keep copies of everything you submit
• •Not requesting your complete claim file before writing the appeal
• •Forgetting to include claim numbers and reference numbers on every document

A Quick Recap: Your Appeal Checklist

• •Read your denial letter and identify the specific reason for denial
• •Note your 180-day deadline and put it on your calendar
• •Request your complete claim file from the insurer
• •Gather medical records, clinical guidelines, and your doctor's letter of medical necessity
• •Ask your doctor about a peer-to-peer review with the plan's medical reviewer
• •Write your appeal letter addressing the specific denial reason with supporting evidence
• •Submit via certified mail (return receipt requested) and consider faxing a copy the same day
• •Keep copies of everything you send
• •Track the review timeline: 30 days (pre-service), 60 days (post-service), or 72 hours (urgent)
• •If denied, review instructions for requesting an external review by an Independent Review Organization

You Don't Have to Do This Alone

Filing an appeal on your own is absolutely possible. Thousands of people do it every year, and many of them succeed. Everything you need to know is outlined in this guide.

That said, if the process feels like too much, especially when you're dealing with a health issue at the same time, services like Appealio exist to help manage the documentation, letter writing, and submission process. There's no shame in asking for help. The important thing is that you don't let a denial letter be the final word.

Because here's the truth: the appeals process exists for a reason. It exists because insurance companies get it wrong sometimes. Nearly half of all internal appeals result in a reversal. The system was built to give you a second chance, but only if you use it.

You have the right to appeal. You have the facts on your side. And now you have the roadmap.