What a horribly misinformed opinion.  NAR is not arguing against the mortgage interest deduction being repealed, it is arguing against the repeal of the state and local tax deduction (for both state income and real estate taxes).  Repealing the SALT deduction is a thinly veiled way to limit the ability of most of the country to itemize their income taxes.  Your example of a couple putting down 80% on a 400k home at a 5% for an annual interest payment of 15k misses one major piece...that 15k will also be combined with that couples state income and real estate taxes.  So, lets imagine this couple pays 10k in real estate taxes (average for a house of this cost) and, combined, pays 12k in state income taxes, in total the family is itemizing 37k in deductions.  So you tell me, does this family- losing 13k in deductions (even with a 3% rate decrease) still end up better off?  Ummm, no!  Repealing SALT deductibility is nothing more than redistribution of wealth from the middle class.