How does the structure of an interest expense cap change the tax benefits of debt?

Abstract

Using an earnings-based structural model, calibrated with US data for the period 2001–2017, we examine how the structure of an interest expense cap for the deduction of interest expense changes the tax benefits of debt. We find that an EBIT (EBITDA) based cap reduces the marginal tax benefits of debt by 6 percentage points (4.6 p.p.) of unlevered firm value for a typical firm. This impact differs across industries due to variations in industry-specific labor and physical capital deployed, and the associated depreciation. An EBITDA-based structure for a cap reduces the differential tax impact of a cap across industries. Our results are widely applicable in determining the cost of debt in the presence of these cap structures, enshrined in the US and OECD countries.