Claim Denials, Appeals, and Follow-Up

Why Denial Management Matters

A claim denial occurs when a payer refuses to reimburse a service as billed. Denials directly affect a practice's revenue cycle, and unresolved denials can result in significant lost income. As a medical biller and coder, your ability to recognize denial types, respond with a timely and well-supported appeal, and track outstanding claims is one of the most valued skills you will bring to any employer. Patient safety also intersects with this work: a denial for medical necessity, if not appealed correctly, may affect a patient's access to care or result in unexpected financial burden.

Common Denial Categories

Understanding the root cause of a denial is the first step toward resolving it. The six most frequently encountered denial types are:

Eligibility denials occur when the patient was not covered by the payer on the date of service, the plan had lapsed, or incorrect insurance information was submitted. Prevention starts at the front desk with real-time eligibility verification before the visit.

Authorization denials happen when a required prior authorization was not obtained before the service was rendered, or the authorization number was not included on the claim. Some services—certain surgeries, imaging studies, and specialist referrals—require advance approval from the payer.

Medical necessity denials are issued when the payer determines that the service was not medically necessary based on the diagnosis submitted, the clinical documentation, or the payer's own coverage policy. These denials often require a clinical appeal supported by physician documentation.

Coding error denials result from incorrect CPT, ICD-10-CM, or HCPCS Level II codes; unbundling; upcoding; or mismatched diagnosis-to-procedure links. Careful code selection and linkage before submission prevents many of these.

Timely filing denials are issued when a claim is submitted after the payer's deadline. Each payer sets its own filing window, which may range from a few months to over a year from the date of service. Always check the payer contract for the exact timeframe. Once this deadline passes, the ability to collect is usually lost.

Duplicate claim denials occur when an identical claim has already been received or processed by the payer. Verify whether the original claim was paid, pending, or truly lost before resubmitting.

The Denial Management Cycle

Effective denial management follows a repeating cycle: identify, categorize, appeal or correct, resubmit, track, and analyze. When a denial explanation arrives on an Explanation of Benefits (EOB) or Electronic Remittance Advice (ERA), read the denial reason code carefully. Most payers use standardized Claim Adjustment Reason Codes (CARCs) and Remittance Advice Remark Codes (RARCs) to explain the action taken. Match the code to the denial category, then choose the correct resolution path—corrected claim, appeal, or write-off.

Writing a Compliant Appeal Letter

An appeal letter is a formal written request asking the payer to reconsider its decision. A strong appeal letter includes:

1. Payer and claim identification — payer name and address, patient name, date of birth, member ID, claim number, date of service, and provider name and NPI.

2. Clear statement of the denial — reference the denial reason exactly as stated on the EOB or denial letter.

3. Clinical rationale — explain, in plain and professional language, why the service was medically necessary or why the code submitted was correct. Cite the specific ICD-10-CM and CPT codes and explain how the documentation supports them.

4. Supporting documentation — attach the relevant progress notes, operative reports, lab results, or physician letters. Never alter clinical documents; submit only authentic records. Altering records is fraudulent and a serious legal and ethical violation.

5. Specific request — state clearly what action you want the payer to take (e.g., reprocess the claim and issue payment).

6. Professional tone — use formal, respectful language throughout. Emotional or accusatory language undermines your credibility.

Always check the payer's appeal deadline before drafting. Missing the appeal filing window can forfeit the right to payment just as missing the original filing deadline does.

Prioritizing Follow-Up on an Accounts Receivable Aging Report

The accounts receivable (AR) aging report organizes outstanding claims by how many days have passed since the date of service or original billing date—typically in buckets of 0–30, 31–60, 61–90, and 90+ days. Claims in the oldest buckets are at greatest risk of exceeding timely filing or appeal deadlines.

When working an aging report, prioritize by:

• Deadline urgency — claims approaching the payer's appeal or timely filing deadline come first.
• Dollar value — higher-value claims warrant immediate attention.
• Denial type — coding errors may be correctable with a simple resubmission; medical necessity denials may require physician involvement and take longer to prepare.

For each denied claim, document your next step and set a realistic follow-up deadline. A written action plan protects the practice legally and ensures nothing falls through the cracks.

Scope of Practice and Safety Reminders

As a biller or coder, you do not practice medicine. Never add, change, or delete a diagnosis or procedure code without direction from the treating provider. If you believe a code is incorrect, bring it to the provider or your supervisor—do not alter it unilaterally. Submitting codes you know to be unsupported by documentation is fraud. Patients depend on accurate billing to protect their benefits and their access to future care.