We received helpful advice from Alberto Alesina, Orazio Attanasio, Felipe Balmaceda, Robert Barro, John Campbell, Christopher Carroll, Stefano Dellavigna, Eduardo Fajnzylber, Mariacristina De Nardi, Pierre-Olivier Gourinchas, Cristóbal Huneeus, Greg Mankiw, Ben Moll, Jonathan Parker, Ariel Pakes, Raimundo Soto, Samuel Thompson, Nicholas Souleles, Motohiro Yogo, and seminar audiences at various institutions. The computations in this paper were run on the FASRC Odyssey cluster supported by the FAS Division of Science Research Computing Group at Harvard University. Laibson and Tobacman acknowledge financial support from the National Science Foundation; Laibson also from the National Institute on Aging (R01- AG-16605), and the Olin Foundation; Repetto from Núcleo Milenio Modelos de Crisis (NS 130017); and Maxted from the NBER Pre-Doctoral Fellowship in Retirement and Disability Policy Research. The research reported herein was performed pursuant to grant RDR18000003 from the US Social Security Administration (SSA) funded as part of the Retirement and Disability Research Consortium. The opinions and conclusions expressed are solely those of the author(s) and do not represent the opinions or policy of SSA, any agency of the Federal Government, or NBER. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of the contents of this report. Reference herein to any specific commercial product, process or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply endorsement, recommendation or favoring by the United States Government or any agency thereof. The views expressed herein are those of the author(s) and do not necessarily reflect the views of the National Bureau of Economic Research.