In an insurance policy, the deductible (in British English, the excess) is the amount paid out of pocket by the policy holder before an insurance provider will pay any expenses. In general usage, the term deductible may be used to describe one of several types of clauses that are used by insurance companies as a threshold for policy payments.

Deductibles are typically used to deter the large number of claims that a consumer can be reasonably expected to bear the cost of. By restricting its coverage to events that are significant enough to incur large costs, the insurance firm expects to pay out slightly smaller amounts much less frequently, incurring much higher savings. As a result, insurance premiums are typically cheaper when they involve higher deductibles. For example, health insurance companies offer plans with high premiums and low deductibles, or plans with low premiums and high deductibles. One plan may have a premium of $1,087 a month with a $6,000 deductible, while a competitive plan may have a premium of $877 a month with a $12,700 deductible. The consumer with the $6,000 deductible will have to pay $6,000 in health care costs before the insurance plan pays anything. The consumer with the $12,700 deductible will have to pay $12,700.

Deductibles are normally provided as clauses in an insurance policy that dictate how much of an insurance-covered expense is borne by the policyholder. They are normally quoted as a fixed quantity and are a part of most policies covering losses to the policy holder. The insurer then becomes liable for claimable expenses that exceed this amount (subject to the maximum sum claimable indicated in the contract). Depending on the policy, the deductible may apply per covered incident, or per year. For policies where incidents are not easy to delimit (health insurance, for example), the deductible is typically applied per year.

Several deductibles can be set by the insurer based on the cause of the claim. For example, a single housing insurance policy may contain multiple deductible amounts for loss or damage arising from theft, fire, natural calamities, evacuation, etc.

There are also deductible reimbursement programs that reimburse a deductible in the event of an automobile, home, boat/yacht or health insurance claim.