This paper explores the influence of the tax assessment period on tax evasion. As the tax assessment period is considered, the disposable income of a tax evader is not realized until the period has passed. This characteristic will distort evaders' consumption decisions and thereby change their evasion decisions as well. According to our analysis, the tax compliance rate is higher than that in traditional models. That is to say, neglecting the impact of tax assessment period will overestimate tax evasion behaviors of taxpayers. Hence, we offer another explanation about ”the puzzle of tax evasion”, which says that the estimated tax evasions in reality are much less serious than those predicted in conventional literature. In addition, government revenues are increased and taxpayers' expected utility levels are decreased as far as the tax assessment period is concerned.