Tax Shelter
  
A tax deduction, really. That interest you pay on your mortgage? It shelters you from taxes you'd owe otherwise. That is, if you had $100,000 in taxable income, but paid $16,000 in interest income on your mortgage this year, then you'd pay taxes on $84,000. That interest deduction would have sheltered at least some of your taxes. And you got to fix the roof.