Notes: Sumario: Many Americans claim Social Security benefits early, though this e aves them with lower monthly payments throughout retirement. We build a lifecycle model that closely tracks claiming patterns under rules, and we use it to predict claiming delays if, by delaying benefits, people were to receive a lump sum instead of an annuity. We predict that current early claimers would defer claiming by a year given actuarially fair lump sums, and the predictions conform with respondents' answers to a strategic survey about the lump sum. In other words, such a reform could provide an avenue for encouraging delayed retirement without benefit cuts or tax increases. Moreover, many people would still defer claiming even for smaller lump sums.