It is common for health and auto insurers to fight over who pays first after a vehicle-related injury, but it is not accurate to say that health insurers “deny any and all” such claims; instead, each policy has coordination-of-benefits rules that they use aggressively to shift costs to the other payer.[1][2]

How coverage is supposed to work

Do health insurers “dump” everything on auto?

What if a patient has no auto insurance?

What this reveals about U.S. insurance

How many people are affected and who “loses”?

Coverage priority after a crash is partly set by state law and partly by the language of each auto and health policy, so the rules do differ across states.[1][2]

California’s rules and typical priority

California is an at‑fault (tort) state, not a no‑fault/PIP state.[3][1] Legally, the at‑fault driver’s liability insurance is responsible for the injured person’s medical costs and other damages, but those liability payments often arrive months or years later, not at the time of treatment.[4][5]

In practice, immediate bills are usually paid (in some combination) by:

• Your health insurance (private, Medi‑Cal, or Medicare) which covers ER, hospital, and outpatient care subject to copays/deductibles, often with a lien to be reimbursed from any settlement.[6][7]
• Optional “MedPay” on your auto policy, which works as small, first‑party no‑fault medical coverage (often 1,000–10,000 dollars) paying accident‑related medical bills for you and passengers regardless of fault and with no deductibles.[5][7][8]

California does not require MedPay; it is purely optional, so many drivers still end up relying mainly on health coverage plus eventual liability settlements.[8][9]

Examples of different state models

Across states, the main structural differences are:

• At‑fault (tort) states without mandatory PIP (e.g., California, most states): liability insurance of the at‑fault driver is primary for damages; optional MedPay may cover medical expenses regardless of fault; health insurance fills gaps and then may assert subrogation rights.[7][1]
• Mandatory no‑fault / PIP states (e.g., Florida, New York, Michigan, Massachusetts, Kansas, Utah, Minnesota, etc.): each driver’s own PIP covers medical expenses (and often some wage loss) up to a statutory limit, regardless of fault, before any liability claim can proceed.[2][10][1]

Policies vary even among no‑fault states:

• In Florida, drivers must carry at least 10,000 dollars of PIP, which generally covers 80 percent of medical bills and 60 percent of lost wages, leaving patients with copays and bills beyond the cap.[10]