Congress defined “affordable” as 9.5% or less of an employee’s household income, mostly to make sure people did not leave their workplace plans for subsidized coverage through the exchanges. But the “error” was that it only applies to the employee — and not his or her family. So, if an employer offers a woman affordable insurance, but doesn’t provide it for her family, they cannot get subsidized help through the state health exchanges.

That can make a huge difference; the Kaiser Family Foundation said an average plan for an individual is about $5,600, but it goes up to $15,700 for families. Most employers help out with those costs, but not all.

“We saw this two-and-a-half years ago and thought, ‘Has anyone else noticed this?'” said Kosali Simon, a professor of public affairs at Indiana University who specializes in health economics. “Everyone said, ‘No, no. You must be wrong.’ But we weren’t, and that’s going to leave a lot of people out.” …