Over time, this is a huge tax break. If their debt is 60 percent of their property, then the excessive deduction in this example is 1.8 percent per annum. Over 20 years, that is a 36 percent tax deduction of the original purchase price. That amounts to a distortionary tax setting and it's one of the reasons why house prices have become so inflated in New Zealand and one of the reasons why residential rental owners have been able to outbid a first-home buyer because they have a tax advantage over their competitor for a house if that competitor is a first-home buyer or an owner-occupier. As the Finance and Expenditure Committee pointed out, there have actually been times recently where real interest rates have been less than zero. 