We study the money-in-the-utility-function model in which agents are heterogeneous in their initial wealth. We show that the Friedman rule is not optimal even if the government uses nonlinear income taxation for redistribution. A positive nominal interest rate raises social welfare because it relaxes the incentive compatibility constraint for highly endowed agents. Although the setup is close to that of da Costa and Werning [Journal of Political Economy (2008) 116, 82–112], who investigate skill heterogeneity, the role of the nominal interest rate in this paper here differs from the one in their model.