What to Do If Your Health Insurance Denies a Claim
Getting a claim denial feels like a dead end — but it's usually not. Insurers deny claims for dozens of reasons, many of which are fixable. About half of all appealed denials are overturned. Here's how to fight back.
Don't pay the bill before appealing. Once you pay, recovering that money is extremely difficult. File your appeal first.
Check the bill for errors before appealing
Many denials are caused by incorrect codes on the original bill. BillScan AI finds them in 15 seconds.
Why Claims Get Denied
Understanding why your claim was denied is the first step. The most common reasons include:
Missing prior authorization
Some procedures require pre-approval from your insurer. If the provider forgot to get it, the claim may be denied — but this is often fixable after the fact.
Wrong or mismatched codes
A typo in a CPT or ICD-10 code can make a covered procedure look non-covered. Ask your provider to review and resubmit with corrected codes.
Out-of-network provider
You may have unknowingly seen an out-of-network doctor. Check whether the No Surprises Act protects you, especially for emergency or hospital-based care.
Service deemed not medically necessary
Your insurer may disagree with your doctor's judgment. A letter of medical necessity from your doctor can often resolve this.
Claim filed late
Providers have a window to file claims — missing it can cause a denial. This is the provider's error, not yours, and they should refile at no cost to you.
Duplicate claim
If the same service was submitted twice, the second claim is auto-denied. The provider needs to verify and resubmit.
Step-by-Step: How to Appeal
Read the denial letter carefully
Your insurer is required to explain why the claim was denied and provide a reference to the specific policy provision they're relying on. The denial letter should also include instructions on how to appeal and the deadline.
Request your claim file
You have the right to request the full claim file — all documents your insurer used to make their decision. This often reveals the exact problem (a wrong code, missing documentation, etc.).
Contact your provider first
Many denials are caused by billing errors the provider can fix by simply resubmitting with corrected codes. Call the billing department, explain the denial reason, and ask if they can refile.
File an internal appeal
Every insurer must have an internal appeals process. Submit a written appeal with a clear explanation of why the denial was wrong, supporting documentation (doctor's notes, medical records, a letter of medical necessity), and a copy of the denial letter.
Request an external review
If your internal appeal is denied, you have the right to an independent external review by a third party. The insurer must abide by the external reviewer's decision. Request this in writing.
File a complaint with your state
Your state insurance commissioner can investigate claim denials. Filing a complaint often speeds up resolution — insurers take state regulatory complaints seriously.
Appeal Deadlines — Don't Miss Them
Most insurers give you 180 days from the date of the denial to file an internal appeal. External review requests typically have a 60-day window after your internal appeal is exhausted. These deadlines are strict — mark them on your calendar the day you receive the denial letter.
What Actually Gets Appeals Overturned
A letter of medical necessity from your doctor explaining why the procedure was required
Clinical guidelines showing the procedure is standard of care for your diagnosis
Proof that the denial was based on incorrect information (wrong codes, wrong dates)
Documentation that prior authorization was obtained or wasn't required
A second medical opinion supporting the original treatment decision
Check your bill for the errors causing the denial
BillScan AI checks every CPT code on your bill against official 2026 Medicare rates and flags coding errors that could be causing your claim to be denied.
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