The term “Cadillac tax” is evocative: It suggests that the health-insurance plans it would tax—through a provision in the Affordable Care Act—are to regular health insurance as a Cadillac is to a Kia. President Obama once described the levy as targeting “really fancy [health insurance] plans that end up driving up costs.”

But what many Americans may not realize is that “Cadillac tax” is in part a misnomer. While some plans that qualify for the tax may be high-end with extra benefits, or “really fancy,” not all of them are. Nor is every employee with an expensive plan a corporate executive. Over time, the number of Americans affected by the tax is expected to increase, as is the revenue the government expects to raise from their plans.