Health insurance reform and part-time work: Evidence from Massachusetts

A concern with requiring employers to provide health insurance to full-time employees is that employers may increase their use of part-time workers to circumvent the mandate. In this paper, we study the effect of the employer mandate in the Massachusetts health insurance reform on part-time work using a difference-in-differences strategy that compares changes in part-time work in Massachusetts after the reform to changes in various control groups. We find strong evidence that the Massachusetts employer mandate increased part-time employment among low-educated workers and some evidence that it increased part-time employment among younger workers. Our estimate of a 1.7 percentage point increase in part-time employment among workers without a college degree suggests that lower-skilled workers may be vulnerable to having their hours cut so that employers do not have to offer them health insurance.