Hence the rush by medical insurers to open their own banks.
"Our choice was either to start a bank or partner with a third party," Anderson said in an interview. UnitedHealth chose to start its own bank, he said, to "provide better service to the customer."
The company also stands to collect fees for maintaining the accounts, handling some disbursements and investing the balances -- and for overdrafts, electronic transfers, even printed checks and monthly statements.
OptumHealthBank has attracted $600 million in health savings account deposits from nearly 400,000 customers. The bank collected more than $34 million in service charges on those deposits in the year that ended June 30, according to its reports to federal banking regulators. Over the same period, it earned $46 million in interest and produced a profit of nearly $33 million for its parent company.
That's a small fraction of UnitedHealth's $4.6 billion in overall profit last year, but it required a capital investment of just $35 million. Moreover, the business is growing fast: Deposits have more than doubled in the last 18 months.
OptumHealthBank was the first bank to be chartered by a medical insurer, but it did not have the field to itself for long. Blue Healthcare Bank, funded by 33 of the 39 member plans of the Chicago-based Blue Cross and Blue Shield Assn., was chartered as a Utah-based thrift last year, and WellPoint's Arcus Bank received approval from the Federal Deposit Insurance Corp. this year.
Arcus is still awaiting formal approval from state regulators in Utah, its home state, but expects to be in operation within six months, said Chief Executive James Rowan.
Utah has been the state of choice for the new charters because state law allows non- financial companies to establish state banks without subjecting the parent company to supervision of federal bank regulators.
Last year, however, the FDIC imposed a moratorium on granting deposit insurance to such banks unless they were owned by a financial services company -- hence WellPoint's attempt to show that its principal business was financial services, not healthcare.
WellPoint had to make that case to the Federal Reserve Board to get a waiver of the FDIC moratorium. In the end, the company reached an agreement that allows it to obtain no more than 15% of its revenue from pharmacy services and disease management, triple the limit initially set by the Fed.
Rowan and Anderson say their banks will benefit customers by offering health savings accounts and healthcare coverage under one roof.
"We want the customer to be empowered," Rowan said.
Whether these new services represent a solution to the nation's healthcare crisis is widely debated.
Health savings accounts are "a step backward," said George Halvorson, chief executive of the giant Kaiser health plan system and outgoing chairman of America's Health Insurance Plans, the health insurance industry's Washington-based lobbying arm. He calls the medical banking trend "off the point of where we need to go" to provide medical coverage to all Americans.
That's because HSAs and their related health insurance policies, which carry high deductibles and offer bare-bones coverage, are particularly beneficial to healthier, younger and wealthier customers. If these customers abandon the conventional insurance market, they will trap those with chronic or serious conditions in a shrinking, high-cost insurance pool.
"Eventually it will be harder and harder to find individual policies that aren't high-deductible plans," said Timothy S. Jost, a law professor at Washington and Lee University in Lexington, Va., and a critic of health savings accounts. "Those plans are great if you're healthy. Other people will find that they have access to health insurance but not healthcare."
HSAs are rooted in a conservative principle called "consumer-directed healthcare," the notion that healthcare expenses have been rising in part because most American consumers, who receive health coverage as an employment benefit, don't know how much their care actually costs.