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ACA Claim Denial Rates: What’s Behind the Numbers

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ACA Claim Denial Rates: What’s Behind the Numbers

According to a 2026 KFF analysis of federal data, insurers offering ACA Marketplace plans through HealthCare.gov denied about 20% of claims in 2024. KFF found that 19% of in-network claims and 37% of out-of-network claims were denied.

For context, the NAIC reported a 16% average claims denial rate across in- and out-of-network claims nationally in 2024. That figure provides a broader point of reference, but it isn’t a direct comparison because the two sources cover different insurance populations and use different reporting methods. The KFF analysis specifically looks at ACA Marketplace plans offered through HealthCare.gov.

Denial rates vary significantly by insurer, network status, state, and plan, but the data shows that claim denials can create a significant revenue-cycle challenge for providers. 

Understanding why these claims are denied is the first step toward preventing avoidable denials. Let’s look at the most common factors behind ACA claim denials and the front-end processes that can help providers reduce them.

So, What’s Driving the Denials?

The roughly 20% denial rate does not represent a universal ACA claim denial rate. The KFF analysis covers insurers offering ACA Marketplace plans through HealthCare.gov, and denial rates vary considerably among insurers. Network status also makes a significant difference, with 19% of in-network claims and 37% of out-of-network claims denied in 2024. 

That variation matters for providers. An individual practice or facility’s denial rate can depend on its payer mix, patient population, network status, authorization requirements, documentation, coding, and other revenue-cycle processes. Providers also can’t assume that every ACA Marketplace plan will have the same denial patterns or requirements.

The data gives us a useful picture of the scale of claim denials among ACA Marketplace plans, but it doesn’t tell us why every claim was denied. To understand that, we need to look at the administrative, coverage, network, and authorization requirements that can affect whether an ACA claim is paid.

Where ACA Claims Run Into Trouble

The data shows that claim denials are a significant issue among insurers offering ACA Marketplace plans through HealthCare.gov. Several factors can contribute to these denials, including administrative requirements:

  • Administrative and Plan Design Errors: Administrative issues are a major documented source of Marketplace denials. In 2024, 25% of reported in-network denial reasons were classified as administrative, while only 5% were attributed to medical necessity.
 
  • Network and Coverage Rules: Narrower provider networks are one reason why out-of-network claims are more difficult to reimburse. Plan-specific exclusions, referrals, prior authorization requirements, and other coverage rules can create additional opportunities for denials.
 
  • Prior Authorization: Prior authorization requirements can create additional administrative work and opportunities for payment delays or denials. It is important for providers to understand payer-specific requirements before services are delivered. 
 
  • Transparency Gaps: Federal reporting has expanded transparency around claims denials. However, publicly available data still does not provide a complete, apples-to-apples picture of all private health plans, particularly self-funded employer plans. 

What This Means for Inpatient Providers

There is no reliable national data showing that inpatient providers have a specific ACA denial rate higher than the Marketplace average. However, the factors behind ACA denials can present particular challenges for hospital-based providers. It’s important to distinguish between a payer’s overall denial rate and an individual facility’s claim denial rate. A facility’s results depend heavily on its patient mix, payer contracts, coding practices, documentation, charge capture, and claims workflows.

The practical issue is preventing avoidable denials rather than assuming every ACA claim will be denied. As with any type of claim, accurate documentation, coding, authorization checks, and complete claims can reduce preventable revenue leakage. Use our article on effective inpatient claim submission as a guide for facility-based providers dealing with complex claim submission requirements. 

How to Keep Denials in Check

Reducing ACA claim denials starts with understanding where they happen and why. Some of the same practices that help prevent denials across the revenue cycle can also help providers navigate the requirements and coverage rules associated with ACA Marketplace plans. From improving coding and documentation to tracking payer trends and using technology to catch potential problems before submission, a few practical changes can make the revenue cycle more efficient. 

  • Improve Your Overall Denial Management: Track denial patterns by payer, denial reason, service, location, and workflow steps so the team can identify recurring problems instead of treating each denial as an isolated event. 
 
  • Audit the Revenue Cycle: Regular revenue-cycle audits can uncover recurring issues with eligibility, coding, documentation, charge capture, billing workflows, and follow-up before they continue to generate denials. 
 
  • Strengthen Coding Accuracy: Make sure documentation supports the codes submitted and establish processes for identifying coding errors before claims reach the payer. 
 
  • Focus on ACA-Specific Rules: Build payer-specific workflows around eligibility, network status, referrals, prior authorization, covered services, and other plan requirements that can affect ACA claims.
 
  • Monitor Payer Trends: Review denial data regularly to identify changes in ACA payer requirements or recurring denial reasons, then update workflows and staff guidance accordingly.
 
  • Use Technology to Catch Preventable Errors: Consider AI medical billing software and other automated tools that can identify potential documentation, coding, charge-capture, or claims issues before submission. Think of AI as a support tool rather than a replacement for knowledgeable RCM staff. 
 
  • Apply AI Where It Adds the Most Value: AI-assisted charge capture and automated quality checks can help identify missed or inconsistent charges earlier in the workflow. This gives providers another opportunity to address potential revenue leakage before claims are submitted. 
 

The goal isn’t to eliminate every denial. It’s to reduce the avoidable ones, learn from the denials that do occur, and build a process that helps prevent the same problems from happening again.

Putting the Data to Work

Claim denials are part of the healthcare revenue cycle, including for providers treating patients with ACA Marketplace coverage. While not every denial can be prevented, understanding payer requirements and identifying recurring problems can help providers reduce avoidable denials and protect earned revenue. The key is having the right processes in place to catch problems early, understand why denials occur, and address recurring issues before they affect more claims.

Claimocity brings charge capture, coding, billing, and revenue cycle management together in one platform, giving practices and facilities greater visibility into the billing process. With tools designed to support accurate charge capture and identify potential issues earlier, we help providers reduce avoidable denials and keep more of their earned revenue moving through the cycle.

Ready to take a closer look at your revenue cycle? Get a Live Demo and see how Claimocity can help your team identify opportunities to improve billing accuracy and reduce preventable denials.

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