In the United States, insurance is regulated by the states under the McCarran-Ferguson Act, with "periodic proposals for federal intervention", and a nonprofit coalition of state insurance agencies called the National Association of Insurance Commissioners works to harmonize the country's different laws and regulations.[46] The National Conference of Insurance Legislators (NCOIL) also works to harmonize the different state laws.[47]


Crop insurance may be purchased by farmers to reduce or manage various risks associated with growing crops. Such risks include crop loss or damage caused by weather, hail, drought, frost damage, insects, or disease.[33] Index-based insurance uses models of how climate extremes affect crop production to define certain climate triggers that if surpassed have high probabilities of causing substantial crop loss. When harvest losses occur associated with exceeding the climate trigger threshold, the index-insured farmer is entitled to a compensation payment.[34]
Professional liability insurance, also called professional indemnity insurance (PI), protects insured professionals such as architectural corporations and medical practitioners against potential negligence claims made by their patients/clients. Professional liability insurance may take on different names depending on the profession. For example, professional liability insurance in reference to the medical profession may be called medical malpractice insurance.
The insured receives a contract, called the insurance policy, which details the conditions and circumstances under which the insurer will compensate the insured. The amount of money charged by the insurer to the Policyholder for the coverage set forth in the insurance policy is called the premium. If the insured experiences a loss which is potentially covered by the insurance policy, the insured submits a claim to the insurer for processing by a claims adjuster. The insurer may hedge its own risk by taking out reinsurance, whereby another insurance company agrees to carry some of the risk, especially if the primary insurer deems the risk too large for it to carry.
There are also companies known as "insurance consultants". Like a mortgage broker, these companies are paid a fee by the customer to shop around for the best insurance policy amongst many companies. Similar to an insurance consultant, an 'insurance broker' also shops around for the best insurance policy amongst many companies. However, with insurance brokers, the fee is usually paid in the form of commission from the insurer that is selected rather than directly from the client.
At the most basic level, initial ratemaking involves looking at the frequency and severity of insured perils and the expected average payout resulting from these perils. Thereafter an insurance company will collect historical loss data, bring the loss data to present value, and compare these prior losses to the premium collected in order to assess rate adequacy.[24] Loss ratios and expense loads are also used. Rating for different risk characteristics involves at the most basic level comparing the losses with "loss relativities"—a policy with twice as many losses would therefore be charged twice as much. More complex multivariate analyses are sometimes used when multiple characteristics are involved and a univariate analysis could produce confounded results. Other statistical methods may be used in assessing the probability of future losses.

In the United Kingdom, The Crown (which, for practical purposes, meant the civil service) did not insure property such as government buildings. If a government building was damaged, the cost of repair would be met from public funds because, in the long run, this was cheaper than paying insurance premiums. Since many UK government buildings have been sold to property companies and rented back, this arrangement is now less common and may have disappeared altogether.
Insurance company claims departments employ a large number of claims adjusters supported by a staff of records management and data entry clerks. Incoming claims are classified based on severity and are assigned to adjusters whose settlement authority varies with their knowledge and experience. The adjuster undertakes an investigation of each claim, usually in close cooperation with the insured, determines if coverage is available under the terms of the insurance contract, and if so, the reasonable monetary value of the claim, and authorizes payment.
Insurance companies earn investment profits on "float". Float, or available reserve, is the amount of money on hand at any given moment that an insurer has collected in insurance premiums but has not paid out in claims. Insurers start investing insurance premiums as soon as they are collected and continue to earn interest or other income on them until claims are paid out. The Association of British Insurers (gathering 400 insurance companies and 94% of UK insurance services) has almost 20% of the investments in the London Stock Exchange.[26] In 2007, U.S. industry profits from float totaled $58 billion. In a 2009 letter to investors, Warren Buffett wrote, "we were paid $2.8 billion to hold our float in 2008."[27]

Products underwritten by Nationwide Mutual Insurance Company and Affiliated Companies. Not all Nationwide affiliated companies are mutual companies, and not all Nationwide members are insured by a mutual company. Subject to underwriting guidelines, review, and approval. Products and discounts not available to all persons in all states. Nationwide Investment Services Corporation, member FINRA. Home Office: One Nationwide Plaza, Columbus, OH. Nationwide, the Nationwide N and Eagle, and other marks displayed on this page are service marks of Nationwide Mutual Insurance Company, unless otherwise disclosed. © 2019 Nationwide Mutual Insurance Company.
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