Claim denials have become one of the most expensive challenges in healthcare revenue cycle management.

The problem is no longer limited to coding errors or missing paperwork. Payers are using increasingly sophisticated review systems, tighter prior authorization requirements, and stricter documentation standards. As a result, providers are spending more time fighting denials and less time focusing on patient care.

According to HFMA, roughly 15% of claims are initially denied. Hospitals and health systems spent nearly $19.7 billion in 2022 appealing denied claims. Some industry analyses suggest those costs have continued to climb as denial volumes increase. The financial impact extends far beyond lost revenue. Every denied claim creates additional administrative work, delays reimbursement, and increases the cost to collect payment.

The good news is that most denials are preventable.

Let’s examine the 15 most common reasons claims get denied in 2026 and what healthcare organizations can do to stop them before they happen.

What Are Medical Billing Denials?

Medical billing denials occur when an insurance payer refuses to reimburse a healthcare provider for services rendered. Unlike rejected claims, which are returned before processing due to errors, denied claims are reviewed by the payer and determined to be ineligible for payment until corrective action is taken.

Nearly 15% of claims submitted to private payers are initially denied, and hospitals spent an estimated $19.7 billion trying to overturn denied claims. Even when providers ultimately win appeals, the process consumes valuable staff time, delays cash flow, and increases the overall cost of reimbursement. 

Whether you’re managing a physician practice, specialty clinic, hospital, or healthcare organization, understanding why claims get denied is the first step toward improving revenue cycle performance.

Medical Billing Denials at a Glance (2026)

Denial Reason	How It Happens	Real-World Example	Prevention Priority
Eligibility Verification Errors	Insurance information is outdated or coverage has changed	Patient changes employers and insurance carrier before an MRI appointment	High
Prior Authorization Failures	Authorization is missing, expired, or incorrect	Surgery is performed after authorization approval expires	High
Coding Errors	Incorrect CPT, ICD-10, or HCPCS codes are submitted	Outdated CPT code is used after annual code updates	High
Missing Modifiers	Required modifiers are omitted or used incorrectly	Bilateral procedure billed without modifier 50	Medium
Lack of Medical Necessity	Documentation does not justify the service	MRI ordered without documenting failed conservative treatment	High
Incomplete Documentation	Clinical records are missing or insufficient	Missing physician notes prevent claim validation	High
Demographic Errors	Patient information is inaccurate	Incorrect member ID causes claim rejection	Medium
Duplicate Claims	Same claim is submitted more than once	Staff resubmits a claim before checking status	Low
Timely Filing Violations	Claim is submitted after payer deadline	Documentation delays cause late submission	High
Coordination of Benefits Errors	Primary and secondary insurance details are incorrect	Secondary coverage is not updated after policy changes	Medium
Provider Credentialing Issues	Provider is not enrolled or credentialed with payer	Newly hired physician bills before enrollment is complete	High
Non-Covered Services	Service is excluded from patient’s plan	Cosmetic procedure billed under non-covered benefits	Medium
Bundling and Unbundling Errors	NCCI rules are not followed	Related procedures billed separately instead of together	Medium
Telehealth Billing Mistakes	Incorrect POS codes or modifiers are used	Virtual visit submitted with incorrect telehealth modifier	Medium
AI-Driven Payer Reviews	Automated systems flag inconsistencies or documentation gaps	Claim denied because supporting documentation does not match billed service	Emerging Risk

Let’s discuss them in detail for your better understanding. 

1- Member ID and Eligibility Verification Failures

Eligibility denials rarely happen because a patient lacks insurance. More often, the claim contains outdated coverage information, an inactive policy, or an incorrect member ID.

A patient may change employers, switch plans during open enrollment, or update dependents without informing the provider. When staff skip real-time eligibility verification, the payer rejects the claim before adjudication even begins.

These denials often appear under eligibility-related CARC and RARC combinations and create avoidable rework for front-desk and billing teams.

What high-performing organizations do:

• Run real-time eligibility checks 48 to 72 hours before appointments.
• Verify coverage again on the date of service.
• Automate eligibility verification for high-volume specialties.
• Track eligibility denial rates by payer.

2- Prior Authorization Expirations and Missing Auth Numbers

Prior authorization denials continue to rise because payers keep expanding authorization requirements across imaging, surgery, specialty drugs, DME, and behavioral health services.

The problem is not always a missing authorization.

In many cases, staff obtain authorization but submit the claim with the wrong authorization number, an expired authorization, or a procedure code that does not match the approved service.

A payer may approve CPT 73721, but the provider bills CPT 73723. That discrepancy alone can trigger a denial.

Watch for:

• Authorization expiration dates
• CPT mismatches
• Units exceeding approved quantities
• Missing authorization reference numbers

3- Diagnosis-to-Procedure Mismatches

This is one of the most common coding-related denial categories.

Payers evaluate whether the ICD-10 diagnosis supports the CPT or HCPCS service billed. When the diagnosis does not justify the procedure according to payer policy, the claim often fails medical necessity review.

For example, billing an advanced imaging study with a diagnosis code that does not meet payer criteria can result in immediate denial.

The procedure may have been clinically appropriate. The diagnosis coding simply failed to support it.

Revenue cycle tip: Audit your highest-volume CPT codes against the ICD-10 codes most frequently linked to denials.

4- Modifier 25 Documentation Failures

Modifier 25 remains one of the most scrutinized modifiers in medical billing.

Providers frequently append Modifier 25 when billing an E/M service on the same day as a procedure. The problem occurs when documentation fails to prove that the E/M service was significant and separately identifiable.

Payers increasingly review these claims because Modifier 25 misuse has historically contributed to overpayments.

Documentation should clearly show:

• A distinct evaluation
• Separate decision-making
• Work beyond the procedure itself

5- Modifier 59 and NCCI Edit Violations

Modifier 59 tells payers that procedures normally bundled together should receive separate reimbursement.

Unfortunately, it is also one of the most misused modifiers in healthcare.

Many denials occur because providers append Modifier 59 without documentation supporting a distinct procedural service.

Payers also use National Correct Coding Initiative (NCCI) edits to identify services that should not be billed separately.

Focus areas:

• Modifier 59
• XE, XP, XS, and XU modifiers
• NCCI edit compliance
• Procedure-to-procedure edits

6- Medical Necessity Denials (CARC 50)

CARC 50 often represents one of the most expensive denial categories because it typically involves high-dollar services.

The denial does not necessarily mean the service lacked medical necessity.

It means the payer did not find enough evidence to prove medical necessity based on its coverage policy.

Advanced imaging, sleep studies, cardiac testing, and specialty procedures frequently fall into this category.

Common root causes:

• Insufficient clinical detail
• Missing symptom history
• Lack of failed conservative treatment documentation
• Diagnosis codes that do not meet payer policy

7- Missing LCD/NCD Supporting Documentation

Medicare contractors often evaluate claims against Local Coverage Determinations (LCDs) and National Coverage Determinations (NCDs).

Many providers focus on CPT and ICD-10 coding but overlook LCD documentation requirements.

For example, a laboratory test may require specific diagnosis codes, physician orders, and clinical documentation before Medicare considers payment.

Without supporting records, the claim becomes vulnerable during review.

Best practice: Maintain specialty-specific LCD and NCD reference guides for providers and coders.

8- Duplicate Claim Denials (CARC 18)

Duplicate claims create unnecessary work and delay reimbursement.

Many billing teams resubmit claims after seeing no response from the payer, only to discover that the original claim remains in process.

The payer then issues CARC 18, indicating a duplicate submission.

The issue often stems from poor claim-status monitoring rather than an actual billing error.

9- Timely Filing Deadline Misses

A clean claim still loses value when staff submit it after the filing deadline.

These denials often reveal workflow problems rather than billing mistakes.

Claims become trapped in work queues because providers have not completed documentation, coders have not finalized charts, or staff continue requesting missing information.

By the time the claim reaches submission, the filing window has closed.

10- Coordination of Benefits Errors (CARC 22)

Patients with multiple insurance plans generate some of the most complex denial scenarios.

CARC 22 frequently appears when providers bill the wrong payer first.

A patient may have Medicare as the primary payer and employer coverage as secondary, yet staff reverse the sequence during registration.

That single mistake can delay payment for weeks.

11- Rendering Provider Credentialing Gaps

Many organizations discover credentialing problems only after claims start getting denied.

A provider may begin seeing patients before enrollment is complete, or a payer may terminate participation because recredentialing requirements were missed.

The claim itself is accurate.

The payer simply does not recognize the rendering provider as eligible for reimbursement.

12- Place of Service (POS) Coding Errors

Place of Service codes tell payers where care occurred.

When providers select the wrong POS code, reimbursement can change dramatically.

Common mistakes include billing office visits, outpatient services, and telehealth encounters under incorrect locations.

Payers often flag these discrepancies automatically.

13- Telehealth Modifier and POS 10 Compliance Issues

Telehealth denials have become more complex as payers continue updating virtual care policies.

Billing teams frequently confuse POS 02 and POS 10 requirements or submit claims without the required telehealth modifiers.

Even small mistakes can lead to denial.

Organizations that provide significant virtual care should conduct quarterly telehealth billing audits.

14- Non-Covered Service Determinations

Not every denial results from an error.

Sometimes the payer simply does not cover the service.

These denials often occur when providers fail to verify benefits before treatment or overlook plan-specific exclusions.

High-cost diagnostics, experimental treatments, and certain preventive services frequently trigger these issues.

15- AI-Driven Payer Edits and Predictive Claim Reviews

This is the denial trend every revenue cycle leader should monitor in 2026.

Payers increasingly use predictive analytics and automated claim-review systems to identify unusual billing patterns, documentation inconsistencies, and potential medical necessity concerns.

The technology allows payers to flag claims before human review occurs.

As a result, providers must focus on clean claims, documentation integrity, coding accuracy, and authorization compliance long before submission.

The organizations with the lowest denial rates no longer rely on denial management alone.

They invest heavily in denial prevention.

How to Reduce Medical Billing Denials

Healthcare organizations cannot eliminate denials completely, but they can significantly reduce them by focusing on prevention rather than appeals.

1- Verify Patient Eligibility Before Every Visit

• Confirm insurance coverage and benefits before services are rendered.
• Check for policy changes, coverage limitations, copays, and deductibles.
• Automate eligibility verification when possible. Eligibility errors are among the most common causes of denials.

2- Improve Patient Registration Accuracy

• Collect complete demographic information.
• Verify patient name, date of birth, insurance ID, and contact details.
• Train front-desk staff to identify missing or inconsistent information.

3- Strengthen Documentation

• Ensure provider notes support the services billed.
• Document medical necessity clearly.
• Use standardized templates and EHR prompts to reduce omissions. Documentation issues account for a significant share of denials.

4- Enhance Coding Accuracy

• Keep coders updated on ICD, CPT, and HCPCS changes.
• Conduct regular coding audits.
• Use coding validation tools to identify errors before claim submission. Coding mistakes are a major source of claim denials.

5- Manage Prior Authorizations Proactively

• Obtain authorizations before services are performed.
• Track authorization numbers and expiration dates.
• Use electronic authorization tools when available. Missing prior authorizations are a frequent denial reason.

6- Submit Clean Claims

• Review claims for missing data, modifier issues, and payer-specific rules before submission.
• Use claim-scrubbing software to catch errors.
• Monitor first-pass acceptance rates as a key performance indicator.

7- Track and Analyze Denials

Create a denial dashboard and monitor:

• Denial rate by payer
• Denial reason codes
• Appeal success rate
• Days to resolution

Root-cause analysis helps identify recurring problems and prevent future denials.

8- Establish a Formal Denial Management Process

A structured process should include:

Organizations that systematically manage denials often see substantial reductions in accounts receivable and denial rates.

• Train Staff Regularly

• Educate registration, billing, coding, and clinical staff on denial trends.
• Share payer updates and policy changes.
• Conduct monthly reviews of common denial causes.

9- Use Automation and Analytics

Modern revenue cycle tools can:

• Verify eligibility automatically
• Scrub claims before submission
• Predict denial risks
• Identify denial patterns

Technology reduces manual errors and improves first-pass claim acceptance.

Key Metrics to Monitor

Metric	Target
Initial Denial Rate	<5%
Clean Claim Rate	>95%
First-Pass Acceptance Rate	>90%
Appeal Success Rate	>60%
Days in A/R	<40 days

Quick Wins

• Verify eligibility for every patient.
• Obtain prior authorizations before treatment.
• Audit top denial reasons monthly.
• Implement claim-scrubbing software.
• Train staff on payer-specific requirements.
• Appeal high-value denials promptly.

Final Thoughts

The denial landscape in 2026 is becoming more complex, but the root causes remain surprisingly familiar.

Eligibility errors, prior authorization failures, coding mistakes, documentation gaps, and credentialing issues continue to account for a large percentage of denied claims.

Healthcare organizations that invest in stronger front-end processes, better documentation practices, and proactive denial analytics will be better positioned to protect revenue and improve operational efficiency.

The goal is not simply to win more appeals.

The goal is to prevent denials from happening in the first place.

Frequently Asked Questions 

1- What is the difference between a denied claim and a rejected claim?

A rejected claim is returned before payer processing, while a denied claim has been processed but payment has been refused.

2- What are the most common causes of claim denials?

Eligibility issues, authorization failures, coding errors, medical necessity concerns, and missing documentation are among the most common reasons.

3- Can denied claims be appealed?

Yes. Many denied claims can be corrected and appealed with supporting documentation.

4- How do claim denials affect revenue cycle management?

Denials delay reimbursement, increase administrative costs, and contribute to revenue leakage.

5- What is a good denial rate?

Many healthcare organizations aim to maintain denial rates below 5%, although benchmarks vary by specialty and payer mix.

6- How can healthcare organizations reduce denials?

Improving documentation, verifying eligibility, obtaining authorizations, monitoring denial trends, and conducting audits can significantly reduce denial rates.