Only about 6% of accountholders in the Employee Benefit Research Institute (EBRI) HSA Database invest their health savings accounts (HSAs), despite that being an important way to increase their account balances. EBRI’s study, “Are HSA Investors Born or Made?” finds some of those investors appear to be inherently prone to invest while others are motivated for different reasons.

Among the few who invest their HSAs, EBRI finds roughly 63% do so in their first year of HSA ownership. EBRI says this suggests these HSA investors are “born”—they are immediately engaged and intentionally invest their balances as quickly as possible. The research report notes that this strategy is made easier by HSA providers that allow for first-dollar investing.

For the other 37% of accountholders, the fact that some HSA providers require a certain threshold before balances can be invested may explain why they were investors at some point in the dataset but did not start out that way. However, the study found, other factors were often involved.

Of HSA investors who EBRI says are “made,” the study finds the two most important characteristics that are associated with transitioning to investing are account tenure and balance. In particular, the analysis shows that a one-year increase in account tenure is associated with a similar increase in the likelihood of investing as an account balance that is roughly $3,250 larger.

Additionally, employee contributions also increase the likelihood of investing, which EBRI suggests signals that engagement is an important determinant in transitioning to investing. The study also found that taking a large distribution is associated with a reduced likelihood of transitioning to investing, which the report says may indicate that accountholders try to build their balances back up after withdrawing money from their HSAs before investing.

To encourage employees to use their HSAs as longer-term savings vehicles, EBRI recommends employers consider two strategies. First, it says the fact that account tenure is closely linked to the decision to invest implies accountholders invest because they become more familiar with their HSAs, they learn more about the benefits of investing, or both. “Therefore, an education strategy could be effective in encouraging accountholders to invest,” the study report says.

Second, finding that account balance size seems to be closely linked with the decision to invest, EBRI says employers could consider contributing some seed money to new accountholders, particularly those with very high deductibles.

As of December 31, 2018, the EBRI Database includes 9.8 million HSAs with $22.8 billion in assets. The 2018 data covers 39% of the universe of HSAs and 42% of HSA assets.