Mortgage interest tax deductibility is needed to treat debt and equity financing of homes equally.Countries that limit deductibility create a debt tax penalty that presumably leads households to shift from debt toward equity financing. The greater the shift, the less is the tax revenue raised by the limitation and smaller is its negative impact on housing demand. Measuring the financing response to a legislative change is complicated by the fact that lenders restrict mortgage debt to the value of the house (or slightly less) being financed. Taking this restriction into account reduces the estimated financing response by 20 percent (a 32 percent decline in debt vs a 40 percent decline). The estimation is based on 86,000 newly originated UK loans from the late 1990s.
The Sensitivity of Household Leverage to the Deductibility of Home Mortgage InterestIn many economies debt financing of housing is penalized relative to equity financing, i.e., interest payments are not fully tax deductible. In the Commonwealth countries -Australia, Canada, New Zealand, and the UK (since 1999) -interest is not deductible; in most European countries (the UK in the quarter century prior to 1999) interest is only partially deductible, being limited by a ceiling on the deductible amount, application of a lower tax rate to the deduction, or both. As a result, the Modigliani-Miller (1958) debt neutrality theorem does not hold; the user cost of capital for owner-occupied housing (through the weighted average cost of capital) is not independent of LTV choice. 1 Knowing how LTVs respond to deductibility limits is thus crucial to understanding how housing choices will be affected by changes in such limits.There are two fundamental problems in explaining LTV behavior. First, the tax penalty on debt usage depends on intricate tax law provisions and the level of debt usage itself. For example, in the UK during the decade 1983-92, there was a penalty only for loan amounts above £30,000, and between 1993and 1999 for some households there was also a penalty for loans below £30,000. In the U.S., a penalty exists for some low-income households, households with low mortgage debt living in states with low house prices and low taxation, and quite high-income households. Thus estimating the penalty for individual households is complicated. Second, it is almost a universal law that LTVs on newly-originated loans are bounded between (are truncated/censored at) zero and one (debt is bounded between zero and house value).Moreover, initial LTVs of first-time home buyers are highly skewed toward the highest lender-permitted LTV (Hendershott, Pryce and White, 2003), while as many as half of older homeowners have zero LTVs (Ling and McGill, 1998). The upper bound of unity or the lender-permitted maximum constitutes credit rationing. Because the economic response to a debt penalty is to reduce debt, the more a borrower is rationed, the less his response to a given penalty will be. The combined effect of LTVs suffering from both truncation and a highly skew...