- Large number of similar exposure units: Since insurance operates through pooling resources, the majority of insurance policies are provided for individual members of large classes, allowing insurers to benefit from the law of large numbers in which predicted losses are similar to the actual losses. Exceptions include Lloyd's of London, which is famous for insuring the life or health of actors, sports figures and other famous individuals. However, all exposures will have particular differences, which may lead to different premium rates.
- Definite loss: The loss takes place at a known time, in a known place, and from a known cause. The classic example is death of an insured person on a life insurance policy. Fire, automobile accidents, and worker injuries may all easily meet this criterion. Other types of losses may only be definite in theory. Occupational disease, for instance, may involve prolonged exposure to injurious conditions where no specific time, place or cause is identifiable. Ideally, the time, place and cause of a loss should be clear enough that a reasonable person, with sufficient information, could objectively verify all three elements.
- Accidental loss: The event that constitutes the trigger of a claim should be fortuitous, or at least outside the control of the beneficiary of the insurance. The loss should be pure, in the sense that it results from an event for which there is only the opportunity for cost. Events that contain speculative elements, such as ordinary business risks or even purchasing a lottery ticket, are generally not considered insurable.
- Large loss: The size of the loss must be meaningful from the perspective of the insured. Insurance premiums need to cover both the expected cost of losses, plus the cost of issuing and administering the policy, adjusting losses, and supplying the capital needed to reasonably assure that the insurer will be able to pay claims. For small losses these latter costs may be several times the size of the expected cost of losses. There is hardly any point in paying such costs unless the protection offered has real value to a buyer.
- Affordable premium: If the likelihood of an insured event is so high, or the cost of the event so large, that the resulting premium is large relative to the amount of protection offered, it is not likely that the insurance will be purchased, even if on offer. Further, as the accounting profession formally recognizes in financial accounting standards, the premium cannot be so large that there is not a reasonable chance of a significant loss to the insurer. If there is no such chance of loss, the transaction may have the form of insurance, but not the substance. (See the U.S. Financial Accounting Standards Board standard number 113)
- Calculable loss: There are two elements that must be at least estimable, if not formally calculable: the probability of loss, and the attendant cost. Probability of loss is generally an empirical exercise, while cost has more to do with the ability of a reasonable person in possession of a copy of the insurance policy and a proof of loss associated with a claim presented under that policy to make a reasonably definite and objective evaluation of the amount of the loss recoverable as a result of the claim.
- Limited risk of catastrophically large losses: Insurable losses are ideally independent and non-catastrophic, meaning that the losses do not happen all at once and individual losses are not severe enough to bankrupt the insurer; insurers may prefer to limit their exposure to a loss from a single event to some small portion of their capital base. Capital constrains insurers' ability to sell earthquake insurance as well as wind insurance in hurricane zones. In the U.S., flood risk is insured by the federal government. In commercial fire insurance it is possible to find single properties whose total exposed value is well in excess of any individual insurer's capital constraint. Such properties are generally shared among several insurers, or are insured by a single insurer who syndicates the risk into the reinsurance market.
When a company insures an individual entity, there are basic legal requirements. Several commonly cited legal principles of insurance include:[3]
- Indemnity – the insurance company indemnifies, or compensates, the insured in the case of certain losses only up to the insured's interest.
- Insurable interest – the insured typically must directly suffer from the loss. Insurable interest must exist whether property insurance or insurance on a person is involved. The concept requires that the insured have a "stake" in the loss or damage to the life or property insured. What that "stake" is will be determined by the kind of insurance involved and the nature of the property ownership or relationship between the persons.
- Utmost good faith – the insured and the insurer are bound by a good faith bond of honesty and fairness. Material facts must be disclosed.
- Contribution – insurers which have similar obligations to the insured contribute in the indemnification, according to some method.
- Subrogation – the insurance company acquires legal rights to pursue recoveries on behalf of the insured; for example, the insurer may sue those liable for insured's loss.
- Causa proxima, or proximate cause – the cause of loss (the peril) must be covered under the insuring agreement of the policy, and the dominant cause must not be excluded
To "indemnify" means to make whole again, or to be reinstated to the position that one was in, to the extent possible, prior to the happening of a specified event or peril. Accordingly, life insurance is generally not considered to be indemnity insurance, but rather "contingent" insurance (i.e., a claim arises on the occurrence of a specified event). There are generally two types of insurance contracts that seek to indemnify an insured:
An "indemnity" policy will never pay claims until the insured has paid out of pocket to some third party; for example, a visitor to your home slips on a floor that you left wet and sues you for $10,000 and wins. Under an "indemnity" policy the homeowner would have to come up with the $10,000 to pay for the visitor's fall and then would be "indemnified" by the insurance carrier for the out of pocket costs (the $10,000).[4][5]
Under the same situation, a "pay on behalf" policy, the insurance carrier would pay the claim and the insured (the homeowner in the above example) would not be out of pocket for anything. Most modern liability insurance is written on the basis of "pay on behalf" language.[4]
An entity seeking to transfer risk (an individual, corporation, or association of any type, etc.) becomes the 'insured' party once risk is assumed by an 'insurer', the insuring party, by means of a contract, called an insurance policy. Generally, an insurance contract includes, at a minimum, the following elements: identification of participating parties (the insurer, the insured, the beneficiaries), the premium, the period of coverage, the particular loss event covered, the amount of coverage (i.e., the amount to be paid to the insured or beneficiary in the event of a loss), and exclusions (events not covered). An insured is thus said to be "indemnified" against the loss covered in the policy.
When insured parties experience a loss for a specified peril, the coverage entitles the policyholder to make a claim against the insurer for the covered amount of loss as specified by the policy. The fee paid by the insured to the insurer for assuming the risk is called the premium. Insurance premiums from many insureds are used to fund accounts reserved for later payment of claims — in theory for a relatively few claimants — and for overhead costs. So long as an insurer maintains adequate funds set aside for anticipated losses (called reserves), the remaining margin is an insurer's profit.
Insurance can have various effects on society through the way that it changes who bears the cost of losses and damage. On one hand it can increase fraud, on the other it can help societies and individuals prepare for catastrophes and mitigate the effects of catastrophes on both households and societies.Insurance can influence the probability of losses through moral hazard, insurance fraud, and preventive steps by the insurance company. Insurance scholars have typically used morale hazard to refer to the increased loss due to unintentional carelessness and moral hazard to refer to increased risk due to intentional carelessness or indifference.[6] Insurers attempt to address carelessness through inspections, policy provisions requiring certain types of maintenance, and possible discounts for loss mitigation efforts. While in theory insurers could encourage investment in loss reduction, some commentators have argued that in practice insurers had historically not aggressively pursued loss control measures - particularly to prevent disaster losses such as hurricanes - because of concerns over rate reductions and legal battles. However, since about 1996 insurers began to take a more active role in loss mitigation, such as through building codes.[7]
