Confusing language in the health care reform law has raised the possibility that millions of Americans living on modest incomes may be unable to afford their employers’ family policies and yet fail to qualify for government subsidies to buy their own insurance. This is a bizarre development that undercuts the basic goal of health care reform — to expand the number of insured people and make their coverage affordable.

The people left in the lurch would be those who had lower incomes but were not poor enough to qualify for Medicaid. They would either have to pay more than they could afford for an employer’s family plan or go without health insurance. The problem arises because the reform law quite properly tries to keep people from dropping affordable employment-based coverage and turning to taxpayer-subsidized coverage on new insurance exchanges, starting in 2014. Only those with coverage deemed “unaffordable” by the health care act would be allowed to receive subsidies.

As Robert Pear reported in The Times recently, the law considers a worker’s share of the insurance premium unaffordable when it exceeds 9.5 percent of the worker’s household income. But that calculation is based on individual coverage for the worker alone, not family coverage, which is much more expensive. That is how the wording of the law has been interpreted by the Internal Revenue Service and the Congressional Joint Committee on Taxation.

Analysts at the Kaiser Family Foundation, a nonpartisan research organization, estimated that in 2008, 3.9 million nonworking dependents were in families in which the worker could afford individual coverage (costing less than 9.5 percent of household income) but not the family plan, which cost, on average, 14 percent of household income.