An important part of the Affordable Care Act (ACA) that has received relatively little research attention is regulatory reform in the small and non-group markets, particularly guaranteed issue and rating restrictions. In order to identify the effect of this part of the ACA, I use states that already had these policies before 2014 as a control group for states newly exposed to them under the ACA. Overall, the reforms do not have any effect in states that expanded Medicaid but are associated with a 1.64 percentage point (or 2.16%) increase in the probability of having health insurance coverage in states that did not expand Medicaid. Effects are seen across broad age range, and are strongest for those whose incomes are slightly above the Medicaid threshold and qualify them for the highest Marketplace subsidy levels.
