Most tax systems create a tax bias toward debt finance. Such debt bias increases leverage and may negatively affect financial stability. This paper models and estimates debt bias in the financial sector, and present novel estimates for investment banks and non-bank financial intermediaries such as finance and insurance companies. We find debt bias to be pervasive, explaining as much as 10 percent of total leverage for regular banks and 20 percent for investment banks, with the effects most pronounced before the global financial crisis. Going forward, debt bias is likely to once again gain prominence as a key driver of leverage decisions, underscoring the importance of policy reform at this juncture.

Risks to macroeconomic stability posed by excessive private leverage are significantly amplified by tax distortions. ‘Debt bias’ (tax provisions favoring finance by debt rather than equity) has increased leverage in both the household and corporate sectors, and is now widely recognized as a significant macroeconomic concern. This paper presents new evidence of the extent of debt bias, including estimates for banks and non-bank financial institutions both before and after the global financial crisis. It presents policy options to alleviate debt bias, and assesses their effectiveness. The paper finds that thin capitalization rules restricting interest deductibility have only partially been able to address debt bias, but that an allowance for corporate equity has generally proved effective. The paper concludes that debt bias should feature prominently in countries’ tax reform plans in the coming years.

Staff Discussion Notes showcase the latest policy-related analysis and research being developed by individual IMF staff and are published to elicit comment and to further debate. These papers are generally brief and written in nontechnical language, and so are aimed at a broad audience interested in economic policy issues. This Web-only series replaced Staff Position Notes in January 2011.

This paper argues that asset price cycles have significant effects on fiscal outcomes. In particular, there is evidence of debt bias—the tendency of debt to increase over the cycle— that is significantly larger for house price cycles than stand-alone business cycles. Automatic stabilizers and discretionary fiscal policy generally respond to output fluctuations, whereas revenue increases due to house price booms are largely treated as permanent. Thus, neglecting the direct and indirect impact of asset prices on fiscal accounts encourages procyclical fiscal policies.

That most corporate tax systems favor debt over equity finance is now widely recognized as, potentially, amplifying risks to financial stability. This paper makes a first attempt to explore, empirically, the link between this tax bias and the probability of financial crisis. It finds that greater tax bias is associated with significantly higher aggregate bank leverage, and that this in turn is associated with a significantly greater chance of crisis. The implication is that tax bias makes crises much more likely, and, conversely, that the welfare gains from policies to alleviate it can be substantial—far greater than previous studies, which have ignored financial stability considerations, suggest.

Corporate income taxation (CIT) in most countries favors debt over equity financing, leading to over-indebtedness. This problem is particularly acute for the financial sector. We estimate financial-stability benefits of eliminating this debt bias. We estimate the long-run effects of CIT on bank leverage and, using a Vasicek-based model of banking crisis losses, we find that eliminating this debt bias could reduce public finance losses in the range of 30 to 70%. These results hold even for conservative estimates of bank-leverage and portfolio-risk effects of CIT changes.

Tax provisions favoring corporate debt over equity finance (“debt bias”) are widely recognized as a risk to financial stability. This paper explores whether and how thin-capitalization rules, which restrict interest deductibility beyond a certain amount, affect corporate debt ratios and mitigate financial stability risk. We find that rules targeted at related party borrowing (the majority of today’s rules) have no significant impact on debt bias—which relates to third-party borrowing. Also, these rules have no effect on broader indicators of firm financial distress. Rules applying to all debt, in contrast, turn out to be effective: the presence of such a rule reduces the debt-asset ratio in an average company by 5 percentage points; and they reduce the probability for a firm to be in financial distress by 5 percent. Debt ratios are found to be more responsive to thin capitalization rules in industries characterized by a high share of tangible assets.