A home mortgage interest deduction allows taxpayers who own their homes to reduce their taxable income by the amount of interest paid on the loan which is secured by their principal residence (or, sometimes, a second home). Most developed countries do not allow a deduction for interest on personal loans, so countries that allow a home mortgage interest deduction have created an exception to those rules. The Netherlands, Switzerland, and the United States each allow the deduction. In Belgium, Ireland and Sweden, only a minor part of mortgage interest is deductible.
adopted from: Wikipedia: Home mortgage interest deduction.
Christian A. L. Hilber, Christian A. L,, and Tracy M. Turner. "The Mortgage Interest Deduction and its Impact on Homeownership Decisions." The Review of Economics and Statistics, October 2014, Vol. 96, No. 4, Pages: 618-637. DOI:10.1162/REST_a_00427.
Abstract: This paper examines the impact of the combined U.S. state and federal mortgage interest deduction (MID) on homeownership attainment, using data from 1984 to 2007 and exploiting variation in the subsidy arising from changes in the MID within and across states over time. We test whether capitalization of the MID into house prices offsets the positive effect on homeownership. We find that the MID boosts homeownership attainment only of higher-income households in less tightly regulated housing markets. In more restrictive places, an adverse effect exists. The MID is an ineffective policy to promote homeownership and improve social welfare.