The number of individuals eligible for HSAs has increased 18% since 2011.

About 13.5 million U.S. residents now have health coverage that is compatible with the health savings account (HSA) program, up 18% from the total recorded a year ago, according to America’s Health Insurance Plans.

AHIP, Washington, has reported that finding in a summary of results from a survey of U.S. health insurers.

A year ago, AHIP said the total number of HSA-eligible U.S. residents had increased 14% from the 2010 total.

Congress created the HSA program in January 2004.

To qualify to contribute income to an HSA free of income taxes, a taxpayer must have coverage that meets minimum and maximum deductible requirements and maximum out-of-pocket expense requirements.

People who have HSA-compatible coverage do not necessarily open or contribute to HSAs.

Between January 2011 and January 2011, the number of large-group plan enrollees eligible to have HSAs increased 26%, to 7.9 million.

In the small group market, the percentage eligible for HSAs increased 9%, to 3 million.

The percentage of all HSA-eligible individuals who are enrolled in large-group plans has increased to 59% this year, up from 55% in 2011.

The percentage of all HSA-eligible individuals who have individual coverage fell to 18%, from 21%, and the percentage who are in small-group plans fell to 22%, from 24%.

In the individual market, about 2.5 million people are eligible for HSA coverage. The number of individuals eligible for HSA coverage has increased 4.8% in the past year, AHIP says.