Nonprofit organizations with 501(c)(3) status are required to file Form 990, Return of Organizations Exempt from Income Tax, with the IRS. The form includes financial statements and background information on the nonprofit, including salaries of key employees (i.e. director, head, officers).
Not as detailed as 10K reports.
Access to these reports must be provided during regular business hours. All 990 Form information is available from the nonprofit or the IRS. Most are available on the Web through the sites below.
Luke Rosiak, a Washington DC based reporter and creator of the Citizen Audit . org website, summarizes the nonprofit scene this way:
"A massive portion of our economy, from hospitals and universities to unions, the Chamber of Commerce and "dark money" political groups such as FreedomWorks, and even the National Football League, are nonprofits, meaning they don't pay taxes.
As a condition of granting tax-free status, the IRS requires nonprofits to file "Form 990s" detailing how they spend their money, who's in charge, and whether there are any conflicts of interest. Nonprofits are required to turn over a copy of their latest filing to anyone who asks, but even in the 21st century, the IRS doesn't provide this important information itself. Worse, it actually collects digital information from all large groups, then actively takes steps to make it less useful, turning it into paper documents".