The Immense and Growing Price of "Tax Expenditures"

Tax expenditures are officially created loopholes that allow individual and corporate taxpayers to reduce their federal liabilities if they engage in certain sanctioned ways. They're called expenditures because they resemble government spending and have been treated as such in federal budgets going back to the 1970s. The biggest tax expenditures (in terms of dollars) include not counting employer-paid health premiums and insurance as compensation, excluding pension contributions and earnings from taxes, the mortgage-interest deduction on up to two homes, depreciation of machinery and equipment, deductions for state and local taxes paid by individuals, and charitable contributions.
Tax expenditures tend to be very popular with the people who benefit from them but they also represent a blatant attempt by the government to engineer behaviors ranging from having children to buying homes rather than renting. As the consensus that our current tax code is overly complicated and inefficient (both in terms of economic activity and revenue generation), all tax expenditures should be on the table for reconsideration and elimination.

http://reason.com/blog/2013/08/22/the-immense-and-growing-price-of-tax-exp