GAO has a tax expenditures website - http://www.gao.gov/key_issues/tax_expenditures/issue_summary.
And there is a nice infograph with a QR code too! Good for GAO! I tried the QR code - it takes you to their 11/29/12 report - Tax Expenditures - Background and Evaluation Criteria and Questions - a very helpful 40- page background report. If you search for "tax expenditure" you can also find this 1979 "primer" report on tax expenditures - also a good read.
I encourage you to take a look.
|2012 GAO Report|