You might find some of these reports useful. Some reports are held as PDF documents within the site and others link to other sites.

Urban Institute Center on NonProfits and Philanthropy, Urban Institute-Brookings Tax Policy Centre
As rising budgetary pressures force policymakers to find ways to reduce spending and increase tax revenue, a new attention has been given to proposals that reduce or eliminate the income...
Stanford University
The purpose of this brief was to find out whether the Great Recession (2008) has led to a scale back in generosity. Have Americans drawn inward and become self-interested in...