By Marlene Satter

Wading in even deeper to the health care arena, Amazon has announced that customers can now pay for appropriate purchases, such as cold medications and glucometers, with their health savings accounts and flexible spending accounts.

CNBC reports that the move allows people with FSAs and HSAs to pay Amazon for out-of-pocket medical expenses with pretax dollars. According to an Amazon spokesperson, “Customers now have the flexibility to use FSA/HSA cards on a wide range of eligible over-the-counter purchases, eliminating the need to pay out-of-pocket or submit receipts for reimbursement.” Prescription purchases may not be far behind.

The feature has already been rolled out, although to little fanfare.

Not only does the move broaden Amazon’s reach into health care—it acquired internet pharmacy PillPack last summer—accepting HSA and FSA purchases also broadens Amazon’s insights into customer needs and spending on health, according to Michael Yang, a health-tech investor with Omers Ventures.

“It’s a back end way for Amazon to learn about consumer purchasing behavior of health care products and services, as it moves more deeply into the space,” Yang told CNBC.

According to some health care experts, this latest step—a pharmacy storefront—could also serve as an entrée into pharmacy and employer benefits, as well as a toe in the door for the market segment that pays cash for prescriptions. Stephen Buck, a health entrepreneur who previously worked at drug distributor McKesson, told CNBC that “consumers with high deductible plans and health savings accounts may be more than willing to pay cash for prescriptions using these accounts.”

About 6 percent of the U.S. population pays cash for prescriptions, accounting for a good-sized segment of the pharmacy market—which amounts to some $450 billion. Making inroads into a cash-paying market offers Amazon a chance to learn more about customer spending in this arena, which could eventually provide it with the ability to navigate the complexities of getting from drug manufacturers through pharmacy benefit managers to the pharmacy itself.