California Health Insurance Claim Denied in 2026? Here’s What to Do First

A denial from your health insurance company can feel scary, especially if you are sick, waiting for treatment, or looking at a large bill. It can also feel personal, as if someone is saying your care does not matter. But in many cases, a denial is not the final answer.

Sometimes the insurer needs more records. Sometimes the provider used the wrong billing code. Sometimes prior authorization was missing. And sometimes the insurance company has denied care that can be challenged through an appeal, a grievance, or California’s Independent Medical Review process.

The most important thing is to slow the situation down. Do not assume you owe the full bill just because you received a denial. Start by finding out exactly why the claim or service was denied, what kind of health plan you have, and what deadline applies.

California is a little more complicated than some states because different types of coverage are handled by different agencies. Many HMOs and managed care plans are regulated by the California Department of Managed Health Care, or DMHC. Some PPO and insurance policies are regulated by the California Department of Insurance, or CDI. Medi-Cal, Medicare Advantage, Covered California eligibility decisions, and self-funded employer plans may each follow different rules.

Useful starting links: DMHC complaint and Independent Medical Review page · California Department of Insurance health complaint page · Covered California appeals page · Medi-Cal state hearing page

Your first step is to find the denial letter or Explanation of Benefits, often called an EOB. The EOB is not a bill. It is the insurance company’s explanation of how it processed the claim.

Look for the claim number, date of service, provider name, denial code, denial reason, amount billed, amount paid, and the amount the insurer says you may owe. Also look carefully for the appeal deadline and the address, fax number, phone number, or online portal where the appeal must be sent.

If the letter is hard to understand, that is normal. Call the insurance company and say, “I received a denial and I need help understanding the exact reason. Please tell me the denial code, the policy or medical rule used, the appeal deadline, and where I should send my appeal.”

Then ask them to send that information in writing. A phone call can be helpful, but if the bill is large or the care is important, you want a written record.

Before you appeal, try to find out what kind of California coverage you have. This matters because the process can change depending on the plan.

If your plan is an HMO or managed care plan, it may be regulated by DMHC. For many DMHC-regulated plans, the appeal is called a grievance. California law requires these plans to have a grievance system. In most cases, the plan must acknowledge a grievance within five calendar days and resolve it within 30 days. If the problem is urgent, the plan must move faster. If the grievance has not been resolved after 30 days, or if the matter is urgent, you may be able to ask DMHC for help.

DMHC complaint page · California Health & Safety Code § 1368

If your plan is a PPO, EPO, or traditional health insurance policy, it may be regulated by CDI. CDI tells consumers to start by contacting the insurer, then file an appeal, grievance, or complaint with the insurer if the issue is not fixed. CDI says the insurer generally must decide within 30 days, and urgent situations should be handled within 72 hours or less if your health is in serious danger.

CDI health insurance problem page · CDI health complaint page

If your coverage is through Covered California, the right process depends on the problem. If the issue is a denied medical service, denied claim, prescription denial, or prior authorization denial, you usually appeal through the health plan first. But if the problem is about Covered California eligibility, financial help, enrollment, renewal, or termination, that may need to go through Covered California’s appeal process instead.

Covered California appeals page

If you have Medi-Cal managed care, be careful with the deadlines. If your Medi-Cal plan denies, delays, reduces, or stops a service, you usually must appeal first with the managed care plan. California’s state hearing page says you generally have 60 calendar days from the notice to file the plan appeal. If the plan appeal does not fix the problem, you generally have 120 calendar days from the plan’s Notice of Appeal Resolution to ask for a state hearing.

Medi-Cal state hearing page

If you have Medicare Advantage, the appeal follows Medicare rules, not the ordinary California commercial insurance process. CMS says a Medicare Advantage reconsideration request generally must be filed within 65 calendar days from the notice of the plan’s decision.

Medicare Advantage appeals page · CMS Medicare Advantage reconsideration page

If your insurance comes from an employer or union, ask whether the plan is fully insured or self-funded. This is very important. Your card may say Anthem, Blue Shield, UnitedHealthcare, Aetna, or Cigna, but your employer may actually be paying the claims itself. If the plan is self-funded, California agencies may have limited authority, and federal ERISA rules may apply instead. Ask your employer or plan administrator for the Summary Plan Description and the claim appeal procedure.

U.S. Department of Labor ERISA health claim guide

A prior authorization denial usually happens before you receive the care. Your doctor may have asked the insurance company to approve surgery, imaging, a hospital stay, a medication, home health care, rehab, mental health treatment, substance use treatment, or an out-of-network referral.

For many California-regulated plans, prior authorization decisions involving medical necessity must be made by a licensed physician or other qualified health care professional who can evaluate the clinical issue. California utilization review rules generally require standard pre-service or concurrent decisions within five business days after the plan receives the information it reasonably needs. Urgent cases generally must be handled within 72 hours, and retrospective reviews after care was already provided generally must be decided within 30 days.

If prior authorization was denied, ask the insurer whether the denial was because the care was not medically necessary, because records were missing, or because authorization was not requested correctly. Ask for the medical policy used, the name and credentials of the reviewer, and whether your doctor can submit more records or request a peer-to-peer review.

California Health & Safety Code § 1367.01 · California Insurance Code § 10123.135

California has passed rules about the use of artificial intelligence, algorithms, and software tools in utilization management. For plans and insurers covered by these rules, AI or software should not be the thing making the final medical necessity decision. The decision still must be made by an appropriate licensed health care professional who considers the patient’s medical history, clinical situation, and treating provider’s recommendation.

This can be useful if the denial letter feels generic. You can ask, “Was AI, an algorithm, or software used in this review? Who made the final decision? What is that person’s license and specialty? Did they review my actual medical records and my doctor’s recommendation?”

CDI AI utilization management guidance

Prescription drug denials are common. The issue may be prior authorization, step therapy, a drug not being on the formulary, a quantity limit, a specialty pharmacy rule, or a claim that the medication is not medically necessary.

California has a helpful rule for many prescription drug prior authorization and step therapy exception requests. For non-urgent requests, the plan generally must respond within 72 hours. For urgent or exigent requests, the timeline is generally 24 hours. The California regulation also says that if the plan or contracted physician group fails to send the required disapproval notice on time, the request may be deemed approved.

If a medication was denied, ask whether the request was treated as prior authorization or step therapy. Ask when the completed request was received, when the denial was sent, and whether the plan met the 24-hour or 72-hour deadline. If the plan missed the deadline, ask whether the medication should be treated as approved under California rules.

California prescription drug prior authorization regulation

A medical necessity denial means the plan decided the care was not necessary under its rules. This can be especially frustrating because your own doctor may believe the care is needed.

For this kind of appeal, your doctor’s support matters. Ask your doctor to write a letter explaining your diagnosis, why the care is needed, what treatments have already been tried, why other options are not appropriate, and what could happen if care is delayed. If you can get the insurer’s medical policy, ask your doctor to explain how your case fits that policy.

Medical necessity denials are especially important in California because they may qualify for Independent Medical Review. IMR means an outside medical reviewer, not the insurance company, reviews the denial. CDI says IMR may be available when a service is denied, delayed, or modified as not medically necessary, when urgent or emergency services are denied, or when experimental or investigational treatment is denied.

CDI IMR page · DMHC complaint / IMR page

Some denials say a treatment is experimental, investigational, not proven, or not standard of care. These denials usually need more than a short appeal.

Ask your doctor whether there are medical studies, clinical guidelines, specialist notes, or treatment records that support the request. If standard treatments have failed, the appeal should explain that clearly. California IMR may be available for certain experimental or investigational treatment denials, depending on the plan and the medical facts.

California IMR regulation

California has important protections for mental health and substance use disorder care. Many California-regulated plans must cover medically necessary treatment for mental health and substance use disorders according to generally accepted standards of care. California rules also recognize that care may need to include more than short-term or crisis treatment. It may include services such as residential treatment, partial hospitalization, intensive outpatient care, and other clinically appropriate levels of care.

This matters if the insurer denies residential treatment, continued stay, eating disorder care, substance use treatment, autism-related treatment, intensive outpatient care, or out-of-network mental health care. In the appeal, it can help to say: “Please explain how this denial complies with California’s mental health and substance use disorder coverage requirements and generally accepted standards of care.”

California Health & Safety Code § 1374.72 · California Insurance Code § 10144.5

Some denials are not really about whether care was medically necessary. They are about the network or the bill.

This can happen when you go to an in-network hospital but are treated by an out-of-network anesthesiologist, radiologist, pathologist, assistant surgeon, or emergency physician. It can also happen after emergency care at an out-of-network hospital.

California has surprise billing protections, and federal No Surprises Act protections may also apply. These rules can limit what you owe in many emergency and certain non-emergency out-of-network situations. If the bill looks like a surprise bill, ask the insurer to reprocess the claim under California surprise billing protections and the federal No Surprises Act.

California surprise billing page · Federal medical bill rights page

Some denials happen because the provider used the wrong code, filed the claim late, forgot to send records, billed the wrong insurer, or did not include a prior authorization number. These are sometimes called administrative denials.

Do not ignore these denials, especially if the bill is large. But do ask the provider’s billing office whether the claim can be corrected and resubmitted. Ask whether the bill can be put on hold while the provider fixes the claim or while you appeal. If the insurer says the claim was filed late, ask the provider whether they have proof of timely filing.

The denial letter should tell you how to appeal. Depending on the plan, the process may be called an appeal, grievance, complaint, reconsideration, or internal review. Do not worry too much about the label. The important thing is to send the appeal to the right place before the deadline.

A simple appeal is often better than a confusing one. Start by saying what was denied and what you want the plan to do. Then explain why the denial should be changed. Attach the denial letter, EOB, medical records, doctor letter, and any other helpful documents.

For example, you can write: “I am appealing the denial of [service, claim, or medication]. My doctor says this care is medically necessary. Please review the attached records and doctor letter. Please send the decision in writing and include the medical policy and clinical criteria used.”

If the matter is urgent, say so clearly: “This is urgent. Waiting for the standard appeal process could seriously harm my health. I am requesting expedited review.”

Independent Medical Review, or IMR, is one of California’s strongest patient protections. It allows an outside medical reviewer to look at certain denials. The reviewer is not the insurance company.

For many DMHC-regulated plans, IMR may be available when a service is denied, delayed, or modified because the plan says it is not medically necessary. IMR may also be available for certain experimental or investigational treatment denials and urgent or emergency care disputes. In many cases, you first file a grievance with the plan or wait 30 days after filing the grievance. But if the issue is urgent, you may be able to ask DMHC for help sooner.

For CDI-regulated insurance, CDI says you usually go through the insurer’s appeal or grievance process first. If the insurer upholds the denial or does not decide within 30 days, you can request IMR. CDI says IMR requests generally must be filed within six months after the insurer upholds the denial, although special circumstances may allow more time.

DMHC complaint / IMR page · CDI IMR page

If waiting could seriously harm your health, do not just file a regular appeal and hope it moves quickly. Ask for expedited review.

Use direct words. Say, “This is urgent. Waiting could seriously harm my health.” Ask your doctor to write a short letter explaining why delay could worsen your condition, cause severe pain, risk loss of function, or threaten life, limb, or major bodily function.

For many DMHC-regulated plans, urgent grievances involving an imminent and serious threat to health, severe pain, or possible loss of life, limb, or major bodily function must be handled quickly, with a written statement on the disposition or pending status no later than three days after receipt.

California Health & Safety Code § 1368.01

California’s largest health plan organizations include Kaiser Permanente, Blue Shield of California, Elevance / Anthem, L.A. Care, Centene / Health Net, UnitedHealth, Inland Empire Health Plan, CVS / Aetna, and Cigna, though the biggest names vary depending on whether you are looking at individual coverage, employer coverage, Medicare Advantage, or Medi-Cal managed care. Covered California also lists participating companies such as Anthem, Blue Shield, Sharp, Kaiser Permanente, Health Net, Molina, Valley Health, Balance, IEHP, and L.A. Care.

CHCF California insurer enrollment report · Covered California

Kaiser Permanente can feel different because it is often an integrated HMO system. The health plan, doctors, hospitals, and medical group may all seem connected. That can make it confusing to tell whether a denial came from the treating doctor, the medical group, or the health plan’s utilization review process. If your Kaiser doctor supports the care, ask the doctor to put that support in the medical record and, if possible, write a letter. Kaiser’s California grievance materials also point members to DMHC help for emergencies, unresolved grievances, and possible IMR rights.

Kaiser grievance form

Blue Shield of California can involve different plan types. Some Blue Shield products may be DMHC-regulated, some may be CDI-regulated, and some employer plans may be self-funded. That means the name “Blue Shield” alone does not always tell you which appeal rules apply. Blue Shield’s grievance information says IMR may be available for medical necessity and experimental or investigational denials, and that in some urgent or experimental-treatment situations, a member may be able to ask for IMR right away.

Blue Shield grievance page

Health Net / Centene is important in both commercial coverage and Medi-Cal managed care. If you have a Health Net commercial plan, you may be dealing with a grievance and possible DMHC or CDI review. If you have Health Net Medi-Cal, watch the Medi-Cal deadlines: generally 60 days to appeal to the plan and 120 days to request a state hearing after the plan’s Notice of Appeal Resolution. Health Net provider materials also describe the California 24-hour urgent and 72-hour standard prescription drug prior authorization timelines, including the deemed-approved rule in certain situations.

Health Net commercial appeals page · Health Net Medi-Cal appeals page · Health Net prescription prior authorization page

L.A. Care, Inland Empire Health Plan, CalOptima, Partnership HealthPlan, and Molina are especially important in Medi-Cal managed care. If you receive a Notice of Adverse Benefit Determination from one of these plans, do not wait. File the plan appeal on time, ask for expedited review if the situation is urgent, and protect your right to a state hearing if the plan appeal is denied.

Medi-Cal hearing page

UnitedHealthcare, Aetna, and Cigna are common in employer coverage, Medicare Advantage, and administrative-services-only arrangements. With these plans, one of the most important questions is whether the plan is fully insured or self-funded. If the plan is self-funded, your employer’s plan document and ERISA appeal rules may matter more than California insurance rules.

U.S. Department of Labor health claim guide

Before submitting the appeal, make sure you understand the denial reason, the deadline, and the correct place to send it. Ask for the medical policy or plan rule. Ask who reviewed the denial. Ask whether the plan is DMHC-regulated, CDI-regulated, Medi-Cal, Medicare Advantage, or self-funded through an employer. If the denial is medical, ask your doctor for a letter. If the care is urgent, say that clearly and ask for expedited review.

A California health insurance denial can feel intimidating, especially when you are sick or facing a large bill. But you do not have to figure everything out at once.

Start with the denial reason. Find out what kind of plan you have. Get the rules in writing. Ask your doctor for support. Submit the appeal before the deadline. And if the denial involves medical necessity, urgent care, experimental treatment, mental health care, or a serious delay, check whether California Independent Medical Review, DMHC, CDI, a Medi-Cal state hearing, Medicare appeal, or ERISA help may be available.