More and more Americans are using a health savings account (HSA) to supplement their retirement savings: As of January 2017, 21.8 million people had opened a HSA, a 9 percent increase in enrollment from 2016.
"It's kind of like this retirement loophole trick," certified financial planner at Betterment Nick Holeman tells CNBC Make It.
While HSAs are not intended to be used for retirement — they're designed for you to use to pay for qualifying healthcare expenses — they're a tax-friendly investment vehicle and can act as a powerful retirement-savings tool if you let your balance compound over years.
In fact, depending on your situation, some financial planners advise maximizing contributions to your HSA even before maxing out your 401(k) plan.
Here's everything you need to know about an HSA.