Reversing a well-publicized effort to improve employee benefits, Walmart is cutting coverage for its part-time employees. New employees who work fewer than 24 hours a week will no longer be eligible for health insurance, and new employees who work between 24 hours and 33 hours a week will no longer be able to put their spouse on their health-care plan. The new policy also docks smokers an extra $10 to $90 each pay period if they want health insurance. Walmart extended benefits to part-time workers a few years ago after complaints that many of its employees could not afford coverage and were eligible for Medicaid. The company—the largest private employer in the United States—cited rising health-care costs as the reason for the change.