We survey companies and find that many use incorrect tax rate inputs into important corporate decisions. Specifically, many companies use an average tax rate (the GAAP effective tax rate, ETR) to evaluate incremental decisions, rather than using the theoretically correct marginal tax rate. We find evidence consistent with behavioral biases (heuristics, salience) and managers' educational backgrounds affecting these choices. We estimate the economic consequences of using the theoretically incorrect tax rate and find that using the ETR for capital structure decisions leads to suboptimal leverage choices and using the ETR in investment decisions makes firms less responsive to investment opportunities.

We examine whether firms hold more cash in the face of tax uncertainty. Because of gray areas in the tax law and aggressive tax avoidance, the total amount of tax that a firm will pay is uncertain at the time it files its returns. The tax authorities can challenge and disallow the firm’s tax positions, demanding additional cash tax payments. We hypothesize that firms facing greater tax uncertainty hold cash to satisfy these potential future demands. We find that both domestic firms and multinational firms hold larger cash balances when subject to greater tax uncertainty. In terms of economic significance, we find that the effect of tax uncertainty on cash holdings is comparable to that of repatriation taxes. Our evidence adds to knowledge about the real effects of tax avoidance and provides a tax-based precautionary explanation for why there is such wide variation in cash holdings across firms.

We survey companies and find that many use incorrect tax rate inputs into important corporate decisions. Specifically, many companies use an average tax rate (the GAAP effective tax rate, ETR) to evaluate incremental decisions, rather than using the theoretically correct marginal tax rate. We find evidence consistent with behavioral biases (heuristics, salience) and managers' educational backgrounds affecting these choices. We estimate the economic consequences of using the theoretically incorrect tax rate and find that using the ETR for capital structure decisions leads to suboptimal leverage choices and using the ETR in investment decisions makes firms less responsive to investment opportunities.

We investigate systematic changes in corporate effective tax rates over the past 25 years and find that effective tax rates have decreased significantly. Contrary to conventional wisdom, the decline in effective tax rates is not concentrated in multinational firms; effective tax rates have declined at approximately the same rate for both multinational and domestic firms. Moreover, within multinational firms, both foreign and domestic effective rates have decreased. Finally, changes in firm characteristics and declining foreign statutory tax rates explain little of the overall decrease in effective rates.