Survey data from the Health and Retirement Study (HRS) suggest that less than 60 percent of individuals age 65 and over who are eligible for SSI receive SSI and administrative data suggest that take-up may be substantially lower than this. The economic literature has identified at least three main barriers to SSI take-up among individuals age 65 and over. First, individuals may not be aware that they are eligible for SSI (SSA 1976, Warlick 1982), which may be a particularly important barrier for individuals for whom being age 65 and over partly determines eligibility. Second, the expected magnitude of benefits affects take-up (McGarry 2000, McGarry and Schoeni 2015), with individuals with lower expectations about benefits less likely to participate in SSI. Third, potential SSI participants may view the application process as confusing and burdensome (Warlick 1982, McGarry 1996, McGarry and Schoeni 2015).
We have designed four letters to test these hypotheses using a randomized controlled field experiment with nearly 4 million individuals. In this study, individuals age 65-80 and who are likely eligible for SSI will be assigned to receive one of these four letter types through US mail or to a control condition (i.e. business as usual). We will track SSI application filing, SSI application allowed (i.e. approved), and SSI payments using administrative data from the Social Security Administration.