This paper examines the effects of government spending shock in a model that features time inconsistency. We build a time-inconsistency edifice on a standard dynamic stochastic general equilibrium (DSGE) model to explore dynamic behavior of macroeconomic aggregates and present-value multipliers. Comparison of the results from a time-inconsistent model (TIM) and a time-consistent model (TCM) reveals that two models deliver markedly different dynamic responses and multiplier effects. A positive government spending shock in TIM delivers a larger decrease in consumption, a smaller decrease in investment and a larger increase in labor and output than TCM. Impact and long-run fiscal multipliers for output in TIM are around 0.28 and 0.01, respectively, which are larger than those in TCM (0.13 and −0.23). The larger multipliers result from the sophistication effect formed by an individual’s perception of their future selves’ behavior. Various sensitivity analyses on important parameters do not reverse the baseline result.