The Medicare Prescription Drug, Improvement, and Modernization Act of 2003 allows individuals enrolled in high-deductible health plans meeting certain requirements to open and fund a health savings account (HSA), an account that an individual can use to pay for health care expenses. Individuals can contribute to an HSA only if they are enrolled in an HSA-eligible health plan. HSAs benefit from a “triple tax advantage”: Employee contributions to the account are deductible from taxable income, any interest or other capital earnings on assets in the account build up tax free, and distributions for qualified medical expenses from the HSA are excluded from taxable income to the employee. This Fast Fact reviews the contribution limits and explores a method for individuals to save over $1 million in their HSA.