Taxpayers' responses to tax-based incentives for retirement savings: Evidence from the Saver's Credit notch

This paper uses the Saver's Credit to analyze taxpayers' understanding of, and responses to, tax incentives. The Saver's Credit is a tax credit designed to encourage retirement savings among low and middle income households; however, the credit's structure creates “notches”, or discontinuous jumps, within a household's budget constraint. These notches provide an incentive to manipulate adjusted gross income to fall just below the level where the credit decreases. I use Public Use Tax Files from the Internal Revenue Service to test whether taxpayers bunch their income at the notch created by the Saver's Credit. I find strong evidence that bunching occurred in response to the credit, which implies that taxpayers claiming the credit understood the incentives for bunching and indeed manipulated their incomes accordingly. I then exploit the discontinuity in credit rates to analyze the credit's impact on retirement contribution behavior using a regression discontinuity approach, and find that the credit failed to generate a statistically significant effect on the level of retirement contributions. These results imply that the Saver's Credit is more effective at providing transfers to low and middle income taxpayers than at increasing retirement contributions.