The Robert Wood Johnson Foundation (RWJF) released a report examining existing state-level dependent coverage expansion efforts and how their impact will differ from the federal dependent coverage expansion contained in the national health care reform law.  The report projects that the impact of the federal expansion will be greater because it is accompanied by the individual insurance mandate. 

From the report: A significant factor contributing to the high uninsured rate among young adults has been the common practice of insurers determining that children are no longer eligible dependents on their parents' plans once they turn 18 (or 23 for full-time students).  The recently-passed federal health reform legislation allows young adults to stay on their parents' plans longer by expanding dependent eligibility until age 26 (effective in late 2010), with the goal of reducing the uninsured reate among this group.  This expansion provision received widespread support during the federal reform debate, as it is both inexpensive and politically palatable.  However, it is worth asking whether this expansion is, in and of itself, likely to have the intended effect on the uninsured rate of the young adult population.    

Full report: The Impact of State Dependent Coverage Expansions on Young Adult Insurance Status (PDF | 274.93 KB)

Robert Wood Johnson Foundation.  (2010).  The impact of state dependent coverage expansions on young adult insurance status.  Cantor, J., Monheit, A., Beloff, D., DeLia, D. and Koller, M.