Which document describes specific operational and financial activities of tax-exempt organizations?

The document that describes specific operational and financial activities of tax-exempt organizations is Form 990. This form is crucial because it provides a comprehensive overview of the organization's mission, governance, finances, and programs. Form 990 is required to be filed annually by exempt organizations to the IRS and serves as a tool for transparency, accountability, and public disclosure. It not only outlines revenue and expenses but also details on compensation for key employees, contributions received, and how funds are utilized to further the organization’s mission.

This level of detail is vital for stakeholders, including potential donors, regulatory agencies, and the general public, to understand how the non-profit operates and how effectively it is using its resources. While other documents such as internal audit reports, financial statements, and tax returns provide valuable information, they do not specifically cater to the operational and financial aspects of tax-exempt organizations in the same comprehensive manner as Form 990.