A provision of the Affordable Care Act that allows insurers to charge smokers higher premiums may have discouraged smokers from signing up for insurance, undercutting a major goal of the law, according to a study published this month.

The surcharges, of up to 50 percent over nonsmokers’ premiums, also showed no sign of encouraging people to quit.

The Affordable Care Act eliminated insurers’ ability to charge higher premiums based on whether a person was sick. But it does allow them to vary premiums with age, geography, family size and smoking status.

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