For many employees faced with the prospect of having to save for rising healthcare costs and for retirement, it's important to understand that it doesn't necessarily have to be an either/or decision.

That’s the finding of Fidelity Investments' latest study which shows that employees who invest in Health Savings Account programs offered by their employer also tend to be bigger savers when it comes to their 401(k) retirement savings programs.

On average, the study found that 401(k) participants who also had an HSA account saved more than twice as much as those 401(k) participants who were not contributing to an HSA account.  At the end of 2010 the average 401(k) saver with an HSA plan had a balance of $170,500, compared to an average balance of only $71,500 for those without an HSA account.

Fidelity Vice President William Applegate said the findings should not be surprising.

“HSA participants understand the tax benefits offered over the long haul, so it’s not surprising they are some of the most active savers in tax-advantaged retirement accounts too," he said. 

The finding that HSA participants tend to be bigger 401(k) contributors holds true across the entire income spectrum, Fidelity researchers found. 

For example, for employees earning only $20,000 to 40,000 per year, the average 401(k) balance in 2010 for participants who also had an HSA account was $30,000, compared to just $19,000 for those who had no HSA account -- a difference of 59%. For those earning $100,000 to 150,000 a year, the average 401(k) balance for those with HSA accounts was $260,000 compared to just $159,000 for those with no HSA -- a difference of 64%.

More broadly, the study found that HSA participants on average contributed 8.9% of annual salary to their 401(k) accounts versus a rate of just 8.2% of salary for those with no HSA account.

Applegate told On Wall Street that HSAs don't appear to cut into the amount employees invest in their 401(k). "The average rate of contribution to a 401(k) for all employees, including those who work at places that don’t offer an HSA, is lower than for employees who are investing in both an HSA and a 401(k) plan,” he said.

Increasing numbers of employers are switching their employee health plans to so-called High Deductible Health Plans (HDHPs) with HSA programs for employees to save tax-advantaged funds to cover the deductible.  The plans are designed to encourage employees and their families to pay more attention to the costs of care, since if HSA funds are not spend in a given year, they roll over into the employees’ account for subsequent years. 

Some 83% of Fidelity HSA plan sponsors provide some level of employer contribution to their employee HSA accounts.

Fidelity’s Applegate said that the study’s findings suggest that “Providing an HSA with an employer contribution is a workplace benefit that can help employees stay on the right path to retirement, saving for their future qualified medical expenses just like they do for their future income needs in a 401(k).”

Savings that are built up in an HSA, if not spent for years, can be withdrawn, Applegate said, but before age 65 the nest egg would be subject to a 20% tax. After 65, withdrawals not for medical expenses are taxed the same as for withdrawals from an IRA.