Learn · OON Underpayments

Zelis Out-of-Network Underpayment Resources

Zelis reprices out-of-network claims to a fraction of your billed charges. Here is how to spot a Zelis reduction, why your appeal goes to the plan, and the data that supports a fair rate.

Written for providers and hospitals, billers, and patients.

Understanding Zelis repricing

Zelis Healthcare is a major healthcare financial technology company owned by Bain Capital and Parthenon Capital Partners. It processes over 155 billion dollars in claims annually for 750+ payers, including major health insurers.

What Zelis does

When an out-of-network claim is submitted to insurance, Zelis may intercept and "reprice" the claim to a lower amount before payment. Zelis applies its repricing tools to determine a payment amount that is often 60 to 80 percent below your billed charges.

How Zelis makes money

Zelis receives a percentage of the underpayment savings from each repriced claim. The larger the gap between your billed amount and the Zelis-approved amount, the more Zelis earns. This creates a financial incentive to lower reimbursement rates.

Active antitrust litigation (as of May 2026)

Zelis is currently a defendant in federal antitrust litigation (In re: Zelis Repricing Antitrust Litigation, Massachusetts federal court) alleging conspiracy to suppress out-of-network reimbursements. A judge allowed the case to proceed to discovery on March 30, 2026. Providers who received out-of-network payments repriced by Zelis may have rights related to this litigation.

This is a developing matter. Treat the status above as a snapshot in time and confirm the current posture before relying on it.

Step one

How to identify Zelis underpayments

Zelis reductions are not always labeled clearly. Use this checklist to spot a repricing on the remittance notice (EOB), then work through the line-by-line process.

Signs on your remittance notice

  • Remark text mentioning "Zelis," "ERS," "Reference Based Pricing," or "Zelis Choice Adjustment"
  • Adjustment code CO-45 (contractual adjustment) with a reduction you did not authorize
  • A network name or repricing company name that does not match the patient's insurance card
  • Payment amounts significantly below your billed charges
  • A reduction with no remark code or explanation (hardest to catch)

Step-by-step identification process

  • Compare the allowed amount on each claim line to your billed charges
  • Look for any reference to Zelis or repricing in the remarks
  • Flag any line where the reduction does not match your expectations
  • Build a spreadsheet over time to identify patterns

The appeal

How to appeal Zelis underpayments

The appeal is a two-step process. Before you start, get the most important point right: you appeal the plan, not the vendor.

Appeal to your insurance company, not Zelis

Zelis is a vendor the insurance company hired to reprice claims. Zelis does NOT owe you payment. The insurance company or plan administrator does. By law, your appeal goes to the plan, not the repricing vendor.
  1. 1

    Appeal directly to your insurance company or plan

    • Find the plan's appeals contact information from the patient's insurance card or EOB
    • Contact the plan's appeals or disputes department
    • Explain that your claim was repriced by Zelis without your authorization
    • Request the plan override the Zelis repricing and pay your full billed amount or a fair market rate
    • Include your billed charges and market-rate benchmarking data
  2. 2

    Provide documentation supporting your appeal

    • Your itemized bill and CMS-1500 or UB-04 claim form
    • Medicare fee schedule rates for your CPT code and geographic region
    • FAIR Health or specialty-specific market benchmarking data
    • Statement that Zelis repricing was not authorized
    • Copy of the remittance notice showing the Zelis adjustment

Build your file

Documentation you will need to appeal a Zelis underpayment

When you appeal to the insurance company, provide this documentation to support your position. Specific regulatory forms vary by plan and state. For detailed step-by-step documentation requirements, see our ERISA appeals resource page. Here are the general document categories.

  • Remittance notice showing the Zelis repricing adjustment
  • Your itemized bill and CMS-1500 or UB-04 claim form
  • Complete medical records supporting medical necessity
  • Medicare fee schedule rates for your CPT code and geographic region
  • FAIR Health or specialty-specific benchmarking data
  • Statement that Zelis repricing was not authorized
  • Required regulatory and appeal forms specific to your plan (varies by insurance company and state)

Prove the fair rate

Resources to find what you should be paid

For out-of-network claims, you have no contract with the insurance company. Use these resources to find what Medicare and commercial insurers typically pay for your services in your geographic area.

Keep reading

Related guides

OON underpayments overview

How repricing vendors cut out-of-network payments, and how to fight back.

Read

MultiPlan underpayments

Identify and appeal MultiPlan / Viant repricing reductions.

Read

Data iSight underpayments

Spot Data iSight repricing and benchmark a fair rate.

Read

ERISA appeals guide

Step-by-step appeal rights and documentation for employer plans.

Read

Appeals glossary

Plain-English definitions of ERISA, IDR, QPA, SPD, and the rest.

Read

Appeal deadlines

Every filing window, in one reference.

Read

Disclaimer

This guide is for informational purposes only and does not constitute legal or medical advice. Appeal It Now provides administrative support and appeal preparation services only; we are not a law firm. Please consult a qualified professional for advice specific to your situation.

Version 2.0 · As of May 2026