On Monday, I mentioned how one of the unintended responses by employers to Obamacare–specifically the fact that a vast majority of them may avoid the law’s penalties by buying flimsy health insurance for their employees — may be a serious challenge to the implementation of the health-insurance exchanges.

Today, another implementation difficulty (or a “bummer, we didn’t think of that when we designed the law”) is surfacing. According to a new report, millions of Americans who are expected to be eligeable for tax subsidies to purchase private insurance on the new health-insurance exchanges may not be able to do so after all because they don’t have a checking account. Over at Kaiser Health News, Sarah Varney reports: 

One in five households in the United States, or about 51 million adults have only a tenuous relationship with a traditional bank, relying instead on check-cashing stores and money lenders, according to the Federal Deposit Insurance Corporation.

The new federal health law which requires most Americans to carry health insurance starting in January presents a particular problem for those households, since most health plans accept a credit card for the first month’s premium payment and then require customers to pay monthly with a check or an electronic funds transfer from a checking account.

Those options won’t work for the so-called “unbankables” looking to purchase health coverage with federal subsidies through online insurance marketplaces, said Dan Schuyler, a director at Leavitt Partners, a firm that is advising private insurers and states on how to comply with the law. “You don’t want to take these millions of unbankable people through the entire enrollment process and then at the end of line say, ‘Ok the only way you can pay for your share of the premium is with a bank account number,’” he said.

The Washington Post’s Sarah Kiff adds:

The Jackson Hewitt report, first reported by Kaiser Health News, focused on uninsured Americans between 100 and 400 percent of the poverty line, who are eligible to receive tax subsidies under the Affordable Care Act.

It found that, in this demographic, the ranks of the unbanked tend to be highest among states that also have high uninsured rates. In Florida, where 24 percent of the non-elderly lack insurance coverage, Jackson Hewitt estimates that 34 percent of those likely eligible for premium subsidies do not have a regular bank account.

The unbanked rate tends to be higher among minority groups. Thirty-three percent of African Americans in the demographic Jackson Hewitt studied did not have a checking account, compared with 23 percent of whites. Among Hispanics, that number stood at 32 percent.

For now, it is hard to tell how much of a problem it will be. For one thing, it will depend on what the different insurance companies’ payment policies are and what the law requires them to do. It’s too bad the drafters of the law didn’t think of that before.