Introduced in 2002, FSAs are used for Internal Revenue Service-defined medical, dependent care or transit expenses. FSAs are often funded by employers through payroll deductions. Specialized processing of FSAs allows for real-time approval at the POS.

HSAs were launched in 2004 and are self-adjudicating; no special processing of HSA cards is required. These accounts are popular with employers because they offer a high deductible for employees (meaning they are low cost for employers).

HSAs are also popular with employees because they view these accounts not just as insurance coverage, but also as investments in their future.

Note: CAGR, which appears in two of the charts, stands for compound annual growth rate.