Insurance companies may be classified into two groups:
- Life insurance companies, which sell life insurance, annuities and pensions products.
- Non-life, general, or property/casualty insurance companies, which sell other types of insurance.
General insurance companies can be further divided into these sub categories.
- Standard lines
- Excess lines
In the United States, standard line insurance companies are insurers that have received a license or authorization from a state for the purpose of writing specific kinds of insurance in that state, such as automobile insurance or homeowners' insurance. They are typically referred to as "admitted" insurers. Generally, such an insurance company must submit its rates and policy forms to the state's insurance regulator to receive his or her prior approval, although whether an insurance company must receive prior approval depends upon the kind of insurance being written. Standard line insurance companies usually charge lower premiums than excess line insurers and may sell directly to individual insureds. They are regulated by state laws, which include restrictions on rates and forms, and which aim to protect consumers and the public from unfair or abusive practices. These insurers also are required to contribute to state guarantee funds, which are used to pay for losses if an insurer becomes insolvent.
Insurance companies are generally classified as either mutual or proprietary companies. Mutual companies are owned by the policyholders, while shareholders (who may or may not own policies) own proprietary insurance companies.
Demutualization of mutual insurers to form stock companies, as well as the formation of a hybrid known as a mutual holding company, became common in some countries, such as the United States, in the late 20th century. However, not all states permit mutual holding companies.
Other possible forms for an insurance company include reciprocals, in which policyholders reciprocate in sharing risks, and Lloyd's organizations.
Insurance companies are rated by various agencies such as A. M. Best. The ratings include the company's financial strength, which measures its ability to pay claims. It also rates financial instruments issued by the insurance company, such as bonds, notes, and securitization products.
Reinsurance companies are insurance companies that sell policies to other insurance companies, allowing them to reduce their risks and protect themselves from very large losses. The reinsurance market is dominated by a few very large companies, with huge reserves. A reinsurer may also be a direct writer of insurance risks as well.
Captive insurance companies may be defined as limited-purpose insurance companies established with the specific objective of financing risks emanating from their parent group or groups. This definition can sometimes be extended to include some of the risks of the parent company's customers. In short, it is an in-house self-insurance vehicle. Captives may take the form of a "pure" entity (which is a 100% subsidiary of the self-insured parent company); of a "mutual" captive (which insures the collective risks of members of an industry); and of an "association" captive (which self-insures individual risks of the members of a professional, commercial or industrial association). Captives represent commercial, economic and tax advantages to their sponsors because of the reductions in costs they help create and for the ease of insurance risk management and the flexibility for cash flows they generate. Additionally, they may provide coverage of risks which is neither available nor offered in the traditional insurance market at reasonable prices.
The types of risk that a captive can underwrite for their parents include property damage, public and product liability, professional indemnity, employee benefits, employers' liability, motor and medical aid expenses. The captive's exposure to such risks may be limited by the use of reinsurance.
Captives are becoming an increasingly important component of the risk management and risk financing strategy of their parent. This can be understood against the following background:
- heavy and increasing premium costs in almost every line of coverage;
- difficulties in insuring certain types of fortuitous risk;
- differential coverage standards in various parts of the world;
- rating structures which reflect market trends rather than individual loss experience;
- insufficient credit for deductibles and/or loss control efforts.
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.
Neither insurance consultants nor insurance brokers are insurance companies and no risks are transferred to them in insurance transactions. Third party administrators are companies that perform underwriting and sometimes claims handling services for insurance companies. These companies often have special expertise that the insurance companies do not have.
The financial stability and strength of an insurance company should be a major consideration when buying an insurance contract. An insurance premium paid currently provides coverage for losses that might arise many years in the future. For that reason, the viability of the insurance carrier is very important. In recent years, a number of insurance companies have become insolvent, leaving their policyholders with no coverage (or coverage only from a government-backed insurance pool or other arrangement with less attractive payouts for losses). A number of independent rating agencies provide information and rate the financial viability of insurance companies.