Leveraged manipulation, which is manifested by reducing the book leverage ratio, not only exacerbates corporate financial risks, but also contributes to systemic financial risks. Taking the 2018 national and local tax merger as a quasi-natural experiment, this paper systematically investigates the impact and mechanism of this important tax reform on corporate leverage manipulation by constructing a difference-in-difference model. The results show that the merger of national and local taxes significantly inhibits the leverage manipulation of enterprises, and at the same time inhibits the two main leverage manipulation methods of off-balance sheet liabilities and real debts, and reducing debt financing costs and increasing commercial credit access are two of the possible influencing mechanisms. The results of heterogeneity analysis show that the inhibition effect of national and local tax merger on corporate leverage manipulation is more significant in the samples with low bank-enterprise linkage, small-scale enterprises, and high tax collection and management intensity. The conclusion of this study provides a new governance idea based on tax reform to curb corporate leverage manipulation, and also provides useful inspiration for comprehensively evaluating the economic consequences of tax reform and effectively deepening tax reform.