Health insurance — how complaints work

In short

A denial is usually not the last word. File an internal appeal within 180 days, with the denial letter, the plan language and a letter from your doctor; if the plan says no again, ask for an external review within 4 months, which the insurer must follow. Very few people appeal (under 1 percent of denied in-network Marketplace claims in 2024), yet appeals often win, and for some Medicare Advantage prior authorization denials nearly all appeals were overturned. For surprise out-of-network bills, use the No Surprises Act. Never give your insurance or Medicare number to someone who calls you, and refuse "free" genetic tests or equipment you did not order.

How complaints work in this industry

• Step 1 is the internal appeal: file within 180 days (6 months) of the denial notice. Insurers must tell you their decision within 15 days for a prior authorization request, 30 days for care already received, and 72 hours for urgent care. HealthCare.gov: internal appeals
• Step 2 is external review by an independent reviewer: file within 4 months after the final denial notice. The insurer is required by law to accept the reviewer's decision. Standard reviews are decided within 45 days, expedited ones within 72 hours. HealthCare.gov: external review
• In urgent situations you may file the internal appeal and the external review request at the same time. HealthCare.gov: internal appeals
• External review is free in the HHS-run process; other processes may charge at most $25 per review. Whether your state or HHS runs it depends on the state and the plan, so ask the plan which process applies. HealthCare.gov: external review
• HealthCare.gov says that if your external review deadline fell between July 1 and August 3, 2026 and your plan uses the HHS process, you may have until October 2, 2026. HealthCare.gov: external review
• California HMO members (for example Kaiser Permanente) can go to the Department of Managed Health Care if a grievance is unresolved after 30 calendar days; the DMHC decides whether the case qualifies for Independent Medical Review, and Kaiser says it will honor the DMHC decision. Kaiser Permanente provider manual, 2023
• Medicare Advantage and Part D plans follow Medicare's own appeal timelines. For example, Aetna Medicare decides expedited authorization appeals within 72 hours and standard ones within 30 calendar days, standard claim-denial appeals within 60 calendar days (no expedited option), and standard Part D redeterminations within 7 days. Aetna Medicare appeals

Your leverage

• Appeals are rare but often succeed. In 2024 HealthCare.gov plans denied 19 percent of in-network claims (about 85 million of 451 million); consumers appealed fewer than 1 percent of them (at least 262,982), and insurers upheld 66 percent of those appeals. KFF, March 2026
• Prior authorization denials are overturned on appeal often: in 2025 data, 67 percent of appealed standard prior authorization denials in Medicare Advantage were overturned, and 43 percent in the HealthCare.gov Marketplace. KFF, August 2026
• For skilled nursing facility admission in Medicare Advantage (June 2024), the 19 insurers studied denied 12 percent of requests, enrollees appealed 18 percent of denials, and insurers overturned 95 percent of appealed denials (2,313 of 2,445). HHS OIG OEI-09-24-00331, June 2026
• The No Surprises Act (in effect since January 1, 2022) generally protects you from surprise out-of-network bills for emergency room visits, non-emergency care at in-network hospitals, and air ambulance services. CMS's help line is 1-800-985-3059, 7 days a week. CMS: know your rights
• Uninsured or self-pay? Providers usually must give a good faith estimate. If a provider bills at least $400 more than its estimate, you can start a patient-provider dispute within 120 days of the initial bill; the fee is $25 and is non-refundable. CMS: dispute a bill
• Many denials are paperwork, not medicine: in 2024 Marketplace data, 25 percent of in-network denial reasons were administrative, 13 percent excluded service, 9 percent missing prior authorization or referral, and 5 percent medical necessity (36 percent "other"). Ask the plan for the exact reason and fix it. KFF, March 2026

Traps

• Missing a deadline ends the right: 180 days for an internal appeal and 4 months for external review under the federal rules; plan documents can set different terms. HealthCare.gov: internal appeals HealthCare.gov: external review
• Denials the plan reports as "other" or "administrative" give little detail; out-of-network claims were denied at 37 percent in 2024 Marketplace data. KFF, March 2026
• The good faith estimate dispute is only for care received without using insurance, on or after January 1, 2022. CMS: dispute a bill
• A denied genetic test can leave you with the full bill: if Medicare denies the claim for a test you did not need, you could owe thousands of dollars. HHS OIG genetic testing alert

Scams to watch for

• "Free" genetic tests: scammers offer cheek swabs by phone, at health fairs or door to door, or mail kits nobody ordered, to collect Medicare information for fraud. Refuse or return kits your doctor did not order. Report to tips.hhs.gov or 1-800-447-8477. HHS OIG genetic testing alert
• Medicare will never call to sell you anything or visit you at home. Give your Medicare number only to your doctor and others who should have it, such as your insurer or your State Health Insurance Assistance Program. Medicare.gov: reporting fraud and abuse
• Report Medicare Advantage or drug plan fraud to the I-MEDIC at 1-877-772-3379 (1-877-7SAFERX). Medicare.gov: reporting fraud and abuse
• Fake insurer calls: Kaiser Permanente says it will never ask for your password by phone or email, and that a caller who says your account needs to be confirmed should be checked by calling customer service directly. Kaiser Permanente: protecting personal information
• Cigna warns about promotions that offer free tests, treatment or services and ask for your insurance information. Cigna: report fraud
• Check each explanation of benefits for services you never received; insurers' fraud units take reports, for example Aetna at 1-800-338-6361 and Cigna at 1-800-667-7145. Aetna: fraud and abuse Cigna: report fraud

By the numbers

• 2024 HealthCare.gov in-network denial rates ranged from 3 to 36 percent by insurer; among parent companies with more than 5 million claims, Elevance Health was lowest (8 percent) and Oscar Health highest (25 percent). KFF, March 2026
• At least 5,881 external appeals were filed in 2024 HealthCare.gov plans, about 4 percent of internal appeals the insurer upheld. KFF, March 2026
• Medicare Advantage skilled nursing facility requests, June 2024 (denial rate; share of appealed denials overturned): UnitedHealth Group 12.9 percent, 99.7 percent; CVS Health (Aetna) 13.5 percent, 98.2 percent; Humana 13.5 percent, 92.1 percent; The Cigna Group 8.8 percent, 96.0 percent; Kaiser Foundation Health Plan 14.0 percent denial rate. HHS OIG OEI-09-24-00331, June 2026