Congressional Research Service, Tax Expenditures: Compendium of Background Material
on Individual Provisions, S. Rep. No. 45, 112th Cong., 2d Sess. (1065 pages):

This compendium gathers basic information concerning approximately
250 federal tax provisions currently treated as tax expenditures. They include
those listed in Tax Expenditure Budgets prepared for fiscal years 2011-2015
by the Joint Committee on Taxation, although certain separate items that are
closely related and are within a major budget function may be combined. The
Joint Committee on Taxation also lists about 30 additional tax expenditures
with de minimis revenue losses (i.e., less that $50 million over 5 years).

With respect to each tax expenditure, this compendium provides:

• The estimated federal revenue loss associated with the provision
  for individual and corporate taxpayers, for fiscal years 2011-2015.
  as estimated by the Joint Committee on Taxation;
• The legal authorization for the provision (e.g., Internal Revenue
  Code section, Treasury Department regulation, or Treasury ruling);
• A description of the tax expenditure, including an example of its
  operation where this is useful;
• A brief analysis of the impact of the provision, including
  information on the distribution of benefits where data are
  available:
• A brief statement of the rationale for the adoption of the tax
  expenditure where it is known. including relevant legislative
  history:
• An assessment, which addresses the arguments for and against the
  provision; and
• Selected bibliography.

The information presented for each tax expenditure is not intended to be exhaustive or definitive. Rather, it is intended to provide an introductory understanding of the nature, effect, and background of each provision. Useful starting points for further research are listed in the selected bibliography following each provision.