Four in Five Charities Use Volunteers. Before undertaking this study, we did not know the proportion of public charities in the United States that involve volunteers in their operations. In 2000, approximately 215,000 charities filed Form 990 or 990EZ with the IRS, the form required of those charities with more than $25,000 in annual gross receipts. We learned that 81 percent of these charities—or an estimated 174,000 organizations— use volunteers in one way or another. Many of these charities are run completely by volunteers. Our estimates do not include the roughly 400,000 small registered charities that do not file annual paperwork with the IRS, virtually all of which are run by volunteers
