Last year, many of the wealthy said they would give less to charity if taxes went up.
Turns out, they weren't kidding.
According to data from Blackbaud, which tracks monthly numbers for more than 3,100 non-profits, total giving in the United States grew by a scant two percent in 2012 compared with 2011. That growth rate is less than half that of 2011, and marks the slowest growth since the depths of the financial crisis in 2009.
(Read more: How Tax Hikes on Rich May Increase Philanthropy)
While Blackbaud doesn't calculate total dollar giving, its results have closely tracked giving totals from GivingUSA. Based on those numbers, Blackbaud expects charitable giving to amount to $304 billion in 2012.
"Last year continued to show signs of a slow recovery for overall fundraising," said Steve MacLaughlin, co-author of the report and director of Blackbaud's Idea Lab.
MacLaughlin said tax policy may have played a role, as wealthy donors prepared for higher tax rates in 2013. But he said natural disasters and more cautious overall giving were largely to blame for the lackluster year in charity.