How to Appeal a Denied Insurance Claim: A Step-by-Step Guide for Practices

To appeal a denied claim: read the denial code and remark code, decide whether the claim needs a correction or an appeal, gather the records that prove your case, and submit a written appeal to the payer before its deadline. Correct and resubmit claims that had your own errors; appeal claims that were right but denied anyway. For Medicare, the first appeal (redetermination) is due within 120 days of the initial decision.

Many practices simply write off denials they disagree with. That is often a mistake: a clear appeal with the right records wins a large share of medical necessity, bundling and authorization denials. The work is in doing it consistently and on time.

Step 1: Understand exactly why the claim was denied

Read the claim adjustment reason code (such as CO-50 or CO-197) and the remark code on the ERA or EOB. They tell you what the payer thinks is wrong. Our guide to denial codes explains the common ones.

Step 2: Choose the right path

Situation	Path
The claim never reached the payer (rejection)	Fix and resubmit as a new claim
Your claim had an error (code, modifier, diagnosis, provider details)	Send a corrected claim
The payer needs information it did not have (records, authorization number)	Reconsideration or records submission, as the payer requires
The claim was right and the payer’s decision is wrong	Formal appeal
The patient’s plan excluded the service	Usually not appealable by you; the patient may have their own appeal rights

Many payers have an informal first step (a reconsideration or reopening) before a formal appeal. Use the payer’s process, because sending the wrong type of request can waste the deadline.

Step 3: Gather the evidence

• The visit note and any treatment plan that supports medical necessity
• Authorization or referral numbers and approval letters
• Proof of timely filing (clearinghouse acceptance reports) for late-filing denials
• The payer policy or clinical guideline that supports the service
• Your contract language, for payment or rate disputes

Step 4: Write a clear appeal

A good appeal letter is short and specific:

1. Patient name, member ID, date of service, claim number and billed amount
2. The denial reason and code you are appealing
3. One or two sentences on why the denial is wrong
4. The policy, guideline or contract language that supports you
5. A list of the attached records
6. What you are asking for: payment of the claim as billed

Avoid long narratives. Reviewers look for the specific criterion the payer says was not met, and the page that proves it was.

Step 5: Submit, track and follow up

Submit through the payer’s portal or the address in its appeal instructions, and keep proof of the date. Track every appeal with its deadline for the payer’s response. If there is no decision within the stated time, call. If the first appeal fails, check whether a second level is available.

Medicare’s five appeal levels

Level	Who decides	Deadline to file
1. Redetermination	Medicare Administrative Contractor (MAC)	120 days from receiving the initial determination
2. Reconsideration	Qualified Independent Contractor (QIC)	180 days from receiving the redetermination
3. Hearing	Administrative Law Judge (ALJ)	60 days from receiving the reconsideration; a minimum amount in controversy applies
4. Review	Medicare Appeals Council	60 days from receiving the ALJ decision
5. Judicial review	Federal district court	60 days from the Council decision; a minimum amount in controversy applies

Medicare Advantage plans have their own appeal process, set by the plan within Medicare rules.

Build a system, not a pile

The practices that recover the most money do three things: they work every denial within days, not months; they keep templates for common appeal types; and they track results so the same denial is prevented at the source next time.

Our denial management team works every denial within 5 business days, including appeals with records, and reports on what caused them. For older claims, see A/R recovery and our timely filing guide.

Frequently asked questions