"[T]his paper, using data from the Health and Retirement Study, specifies how much longer households in each SES quartile would need to work to maintain their pre-retirement standard of living and compares those optimal retirement ages with their planned retirement ages to calculate a retirement gap.... The analysis shows that households in lower-SES quartiles have larger retirement gaps, and this pattern remains true even after controlling for late-career shocks. In short, the most vulnerable have the largest retirement gaps, and these gaps arise from poor planning rather than late-career shocks."