An insurer operating nationwide holds dozens of separate licenses. State-based regulation is the defining structural feature of the American insurance market.
The legal basis for state authority
Federal legislation in the mid twentieth century affirmed that regulation of insurance is left to the states, subject to limited federal exceptions.
That framework followed litigation over whether insurance constituted interstate commerce, and it settled a question that had been contested for decades.
The result is that insurance escaped the federal consolidation that reshaped banking and securities regulation, keeping supervision with state departments.
What a state department actually does
State insurance departments license insurers and producers, review policy forms, approve or monitor rates, and examine companies for financial solvency.
Solvency regulation is the core function, since a policy is a promise to pay in the future and its value depends entirely on the insurer surviving to honor it.
Departments also handle consumer complaints and can take action against practices in claims handling, which is where most consumer contact occurs.
How coordination happens across states
An association of state regulators develops model laws, accreditation standards and shared systems that states adopt individually, producing partial rather than complete uniformity.
Financial examination is coordinated so that a lead state examines a group, with other states relying on that work rather than duplicating it.
The coordination reduces duplication but preserves each state's authority to diverge, which is why identical products can be unavailable across a state line.
Why products differ between states
Policy forms require approval, and states impose different mandates about what coverage must be included and what exclusions are permitted.
Rate regulation also varies, with some states requiring prior approval of rates and others allowing use with subsequent review.
Those differences mean an insurer's product in one state may not exist in the same form next door, and pricing reflects local rules as well as local risk.
The surplus lines exception
Risks that admitted insurers will not write can be placed with surplus lines carriers, which are not licensed in the state but are eligible to write there.
Surplus lines policies generally escape form and rate regulation, which is what allows unusual risks to be covered at all.
They also fall outside state guaranty fund protection, which is the tradeoff attached to the flexibility the channel provides.