Under the Affordable Care Act (ACA) and at the request of a plan participant or beneficiary, a group health plan or health insurer must assign an impartial third party, known as an independent review organization (IRO), to perform external review of a final benefits denial under the plan's internal administrative claims procedures (see Practice Note, External Review Under the ACA).

Following its review, the IRO may uphold or overturn the plan's decision to deny coverage. The cost for an IRO to conduct external review must be borne by the plan, though the process may require a nominal filing fee to be paid by the participant or beneficiary.

An IRO also may review a health care provider's claims, systems, or unallowable costs under a Corporate Integrity Agreement (CIA) entered into with the Department of Health and Human Services, Office of Inspector General, as part of a civil health care fraud settlement.