ShErry a. gliEd, dan p. ly and lawrEncE d. BrownThe medical savings account model of health insurance in the United States combines a high-deductible health insurance plan 1 with a dedicated savings account used to pay expenses incurred below the deductible. Savings in the plan can roll over from one year to the next and, after some predefined period during which they are dedicated to health spending, can be used for non-health-related expenses. 2 In principle, this model combines the incentives for frugal use of health services that exist in high-deductible health insurance with assurance that the funds required in the event of true medical need will be available.In the United States, interest in and experimentation with this model began, on a very small scale, in the mid-1970s. Beginning in 1996, the use of this model in private, voluntary health insurance in the United States was promoted through a series of tax incentives. The first of these incentives, a limited demonstration project (capped at a maximum of 750 000 enrollees), was passed as part of the Health Insurance Portability and Accountability Act of 1996, which allowed self-employed individuals and businesses with fewer than 50 employees who were covered under qualified high-deductible health plans to make tax-exempt contributions to medical savings accounts.When the demonstration project ended enrolment in 2000, about 100 000 individuals had signed up. Next, in 2002, the Treasury Department, which directs the Internal Revenue Service, issued a notice indicating that an employer's contribution to an account set aside for