Tax policy and investment in major U.S. macroeconomic econometric models

In an analysis of six major U.S. quarterly models, the predicted results of tax incentives for investment are found to vary widely. Differences are traced to critical specifications in investment equations. When appropriately revised investment equations are reestimated the role of tax parameters is much reduced, particularly among the high outliers, and the variance among the models is narrowed decidedly. Full model simulations of revised equations suggest that current and proposed incentives such as the investment tax credit and accelerated depreciation are not cost-effective. Increases in investment approximate only half of static tax losses, and budget deficits widen.