April 10, 2025

Your Insurance Company Denied Your Claim — Here's How to Fight Back

If your insurance company just denied your claim, you are not alone. Health insurers in the United States issue an estimated 450 million claim denials per year. That number is staggering on its own, but the truly alarming part is what happens next: fewer than 1 percent of people appeal. The vast majority accept the denial and either pay out of pocket or go without the care they need.

This is exactly what insurers are counting on. Denials are a business strategy, not a medical judgment. And the data shows that when people do fight back, they win far more often than they expect.

You Are Not Alone

Claim denials affect millions of Americans every year. According to data from the Affordable Care Act marketplace plans, denial rates vary by insurer but commonly range from 10 to 25 percent of all claims submitted. Some insurers deny more than one in five claims.

The types of claims denied span every category of healthcare: diagnostic imaging, prescription medications, specialist visits, surgeries, mental health treatment, and emergency room visits. No type of care is immune from denial.

If you are reading this because your claim was denied, understand that the denial is the beginning of a process, not the end of one. The system has multiple levels of review specifically because denials are so common and so frequently wrong.

Why Claims Get Denied

Understanding why your claim was denied is the first step to fighting it. Here are the most common reasons:

  • Medical necessity:The insurer determined that the treatment was not medically necessary. This is often a disagreement between the insurer's criteria and your doctor's clinical judgment.
  • Prior authorization: The required pre-approval was not obtained before the service was provided.
  • Out-of-network provider:The provider was not in your plan's network.
  • Coding errors: The claim was submitted with incorrect procedure codes or diagnosis codes.
  • Coverage exclusion: The insurer claims the service is not covered under your plan.
  • Timely filing:The claim was submitted after the insurer's filing deadline.
  • Incomplete information: The insurer says it needs more documentation to process the claim.

Many of these reasons are procedural, not clinical. Coding errors and missing documentation can often be resolved with a phone call to your provider's billing department. But for denials based on medical necessity, coverage disputes, or prior authorization, you will need to go through the formal appeals process.

Your Rights Under the ACA

The Affordable Care Act established important protections for consumers facing claim denials. Under the ACA:

  • You have the right to appeal any denialthrough your insurer's internal appeals process.
  • You have the right to an external review by an independent third party if your internal appeal is denied.
  • Your insurer must provide a clear explanation of why your claim was denied and instructions for how to appeal.
  • You have the right to request your complete claim file, including the clinical criteria used to make the denial decision.
  • Urgent claims qualify for expedited review, with decisions required within 72 hours for internal appeals.

Some state laws provide even stronger protections beyond what the ACA requires. (Medicare Advantage and Medicaid follow separate appeal processes — see our Medicare Advantage appeal guide if you're on an MA plan.)

The Escalation Process Most People Don't Know About

Most people think of an insurance appeal as a single event: you write a letter, and the insurer says yes or no. In reality, there is a multi-step escalation process that progressively increases pressure on the insurer. Each step raises the stakes:

  1. Internal appeal (Day 1): Your formal written appeal to the insurer. This is required before you can access external review in most states.
  2. Follow-up letter (Day 14-30):If the insurer hasn't responded within the required timeframe, a follow-up letter citing their obligation to process appeals within regulatory deadlines puts them on notice.
  3. State insurance commissioner complaint (Day 30):Filing a formal complaint with your state's Department of Insurance triggers a regulatory investigation. The insurer must respond to the regulator, not just to you. Learn more in our guide on filing a commissioner complaint.
  4. External review request (Day 45): An independent medical reviewer evaluates your case. If they side with you, the decision is binding on the insurer.

Most denials are overturned before you even reach external review. The combination of a well-written appeal, a persistent follow-up, and regulatory pressure from the commissioner's office is enough to resolve most cases.

The Odds Are in Your Favor

Here is the data point that insurers don't want you to know: across multiple state and federal studies, the majority of appealed health insurance denials are overturned in the patient's favor. The exact rate depends on the type of denial, the state, and whether the appeal reaches external review. But the consistent finding is that appealing works.

Think about what that means. Insurers are denying claims that they know are likely to be overturned on appeal. They do this because the math works in their favor: if 99 percent of people never appeal, the insurer saves money on every denial that goes unchallenged, even if the denial would not survive scrutiny.

When you appeal, you move from the 99 percent who accept the denial to the 1 percent who fight it. And in that group, the success rate is remarkably high.

Step by Step: What to Do Right Now

If your claim was just denied, here is your action plan:

  1. Read your denial letter carefully. Identify the specific reason for the denial, the plan provision cited, and your deadline to appeal.
  2. Request your claim file. You have the right to see the clinical criteria the insurer used. This often reveals weaknesses in their reasoning.
  3. Talk to your doctor.Ask if they will write a letter of medical necessity supporting the treatment. Ask if they will do a peer-to-peer review with the insurer's medical reviewer.
  4. Write your appeal letter.Be specific: address the exact denial reason, cite clinical guidelines, reference your state's insurance regulations, and include supporting documentation. Read our guide on writing an effective appeal letter.
  5. Send it certified mail. Email and fax can be lost or ignored. Certified mail creates a legal record that the insurer received your appeal.
  6. Track your deadlines. Note when the insurer must respond and be prepared to follow up and escalate.

Or Let DenyBack Handle the Entire Escalation

The appeals process works, but it takes time, research, and persistence. If you would rather not spend hours writing letters and tracking deadlines, DenyBack handles the entire escalation sequence for $39.

You upload your denial letter, and DenyBack generates a personalized appeal package with state-specific regulatory citations, physically mails each document to the right address via USPS certified mail, and escalates automatically on a schedule: appeal on Day 1, follow-up on Day 14, commissioner complaint on Day 30, external review request on Day 45. You don't write a single letter. You don't visit the post office. You don't track a single deadline.

But whether you use DenyBack or handle it yourself, the most important thing is that you appeal. The system is designed to make you give up. Refuse to give up.