How to Appeal a Denied Insurance Claim

If an insurance company denied your claim, that denial is not the final word — you can usually appeal, and a well-documented appeal can change the outcome. A denial letter is the start of a process, not the end of your case. Below is exactly how to read your denial, gather the right evidence, write an appeal that gets read, and escalate if the insurer still says no.

First, Find Out Why They Denied It

Start by understanding the denial. Claims are denied for everything from clerical slip-ups to genuine disputes over the facts, and the reason shapes your next step. Read the denial letter closely; it should tell you why. Common reasons include:

• Missing information or paperwork errors — a blank field, a wrong code, a missing form.
• Missed deadlines — the claim or required documentation came in late.
• "Not medically necessary" — the insurer disputes that treatment was needed.
• Insufficient documentation — they say the records don't support the claim.
• Coverage disputes — they argue the policy doesn't cover the loss.

A clerical denial is often fixed with a phone call and a corrected form. A "not medically necessary" denial is a substantive dispute resolved with evidence. Identify which one you're dealing with before you do anything else.

Gather Your Evidence Before You Write a Word

An appeal is only as strong as what backs it up. Build your file first:

• Request the insurer's claim file. Ask for the documents behind the decision, including the specific policy language relied on. Seeing the insurer's reasoning tells you what your appeal needs to answer.
• Pull your complete medical records. Get the full record, not just the bills — physician notes, test results, imaging, and treatment history that prove what happened and what it cost.
• Get a letter of medical necessity. If the denial questions whether care was needed, a letter from your treating doctor explaining why the treatment was necessary is often the single most persuasive document in the file.
• Document everything beyond the bills. Lost wages, out-of-pocket costs, a journal of how the injury affected daily life, and witness statements all add weight. (See our guide on how to write a witness statement.)

How to Write a Clear, Persuasive Appeal Letter

A persuasive appeal letter is organized, specific, and tied directly to evidence. Structure it so a busy reviewer can follow it in one pass:

• Open with the basics — your name, policy and claim numbers, and the date of the denial.
• State plainly that you are appealing and name the specific reason given for the denial.
• Rebut that reason point by point. For each argument, point to the exact document that disproves it: "The denial states X; the attached medical record dated [date] shows Y."
• Attach and label every exhibit so nothing has to be hunted for.
• Close with a clear ask — that the insurer reverse the denial and pay the claim — and keep the tone professional, never angry.

Don't argue in generalities. Strong appeals connect each piece of evidence to the precise reason the claim was denied. And always keep a complete copy of everything you send, with proof of delivery.

The Appeal Process, Step by Step

Most appeals move through two stages: an internal appeal with the insurer, and — if that fails — an external review by a neutral third party. Here's the sequence:

The Internal Appeal

This is your first and most important stage. A different team inside the insurance company — people who had nothing to do with the original denial — reviews your file fresh. That fresh review, paired with strong new evidence, is exactly why a detailed appeal is so effective. Insurers generally must decide within a set window, and the length of that window varies by the type of claim and the policy or plan involved — so check your denial letter and policy for the deadline that applies to you, and don't assume you have more time than you do. Follow up about once a week to confirm they have everything, stay professional, and document every interaction.

If the Insurer Still Says No: External Review

If the internal appeal fails, you may be able to ask for an external review by a neutral Independent Review Organization. Unlike the internal appeal, an external reviewer's decision is generally binding on the insurer. For many health-insurance denials, you can request external review through the Colorado Division of Insurance, which confirms eligibility and assigns the case to an independent reviewer. External review isn't available for every kind of claim, and the deadlines and rules differ by claim type — so confirm what applies to your situation before you rely on it.

Watch the Deadlines

Appeals are deadline-driven, and missing one can end your case. Your policy and your denial letter set the clock for filing an internal appeal — read them promptly and carefully, because some policies impose shorter windows than you'd expect, and they vary by claim type. Separately, if your denial relates to a personal injury, Colorado sets a statute of limitations for filing a lawsuit — generally three years for motor-vehicle injury claims (C.R.S. § 13-80-101(1)(n)) — the outer boundary for any related legal action. Don't let the appeal process eat up the time you'd need to take the matter to court.

When the Denial Might Be Bad Faith

Sometimes a denial isn't an honest disagreement — it's an insurer acting unreasonably to avoid paying a legitimate claim. That's insurance bad faith, and Colorado law provides remedies for it. Warning signs include:

• Denying a clearly covered claim with no real explanation.
• Dragging out the process or ignoring your communications.
• Refusing to investigate, or demanding the same documents over and over.
• Offers that bear no relationship to your documented losses.
• Misrepresenting your policy's terms.

If your denial fits this pattern, you may have rights beyond the appeal itself. Colorado law can give policyholders a claim against an insurer that handles a first-party claim unreasonably — including the possibility of recovering two times the covered benefit plus attorney fees and costs for an unreasonable delay or denial (C.R.S. §§ 10-3-1115 and 10-3-1116), on top of any common-law bad-faith claim. The deadlines for these claims vary by theory: a common-law bad-faith claim is generally subject to a two-year limitations period (C.R.S. § 13-80-102), and a claim for breach of the insurance contract generally three years (C.R.S. § 13-80-101(1)(a)). The practical takeaway is to act promptly and have the timing confirmed for your specific situation. Curious why insurers deny in the first place? See why insurance companies deny claims, and our tips on dealing with insurance adjusters.

When to Call a Lawyer

You can handle a straightforward appeal yourself. But call an attorney when the stakes are high, the denial keeps standing, or something feels off — especially if you see bad-faith red flags, if your injuries are serious, or if the insurer simply won't engage. The right time is usually before you've burned through your deadlines.

At Conduit Law, we'll read your denial, build the appeal, and, where an insurer has handled a claim unreasonably, pursue the remedies Colorado law provides.

A Few Quick Answers

Can I appeal a denial for a pre-existing condition? Often, yes. For many types of health coverage, federal law limits an insurer's ability to deny coverage based on a pre-existing condition. Whether that protection applies depends on the kind of plan and claim involved, so it's worth confirming for your particular policy — but a pre-existing-condition denial is frequently appealable.

What if my external review is also denied? A binding external denial usually ends the administrative process — but it doesn't always end your options. Depending on the facts, you may still have legal claims worth pursuing. Talk to an attorney before you assume the door is closed.

Free Consultation

If your claim was denied, it helps to get advice before a deadline approaches. Call Conduit Law at (720) 432-7032 for a free, no-pressure consultation. We'll give you a clear read on whether your denial is worth appealing and how we would approach it.