Supporters of ObamaCare acknowledge it will have some unintended consequences. Yet surprisingly little attention has been focused on the law’s most problematic provision: government subsidies to help individuals and families purchase health insurance.

This new entitlement—which the chief actuary of the Centers for Medicare and Medicaid Services estimates will cost more than $100 billion per year once it is fully implemented—will damage the country’s long-term fiscal outlook. It also will introduce far-reaching negative effects on rewards to work and bizarre new inequities into American life.

The health law establishes insurance exchanges—regulated marketplaces in which individuals and small businesses can shop for coverage—and minimum standards for the insurance policies that can be offered. Because the policies will be so costly, there’s a subsidy for buyers that phases out as family income rises. This sounds reasonable—but the subsidies required to make a “qualifying” insurance policy affordable are so large that their phaseout creates chaos.