Indeed, administration officials and senior Democratic lawmakers say it’s not a loophole but the result of a well-meaning effort to simplify rules for deciding who will get help with insurance costs under the new health care law. Instead of a hodgepodge of rules, there will be one national policy.

“This simplification will stop people from falling into coverage gaps and may cause some to be newly eligible for Medicaid and others to no longer qualify,” said Brian Cook, spokesman for the Centers for Medicare and Medicaid Services.