Becoming a nonprofit corporation does NOT automatically make you tax exempt from federal taxes. That designation is given upon approval for tax exempt status from the IRS. Either a streamlined application (for 501(c)(3) organizations that meet the requirements of that form) or form 1023 or 1024 will be filed for organizations seeking tax exemption. Once approved, the organization will receive a “determination letter” from the IRS with the organization’s status. This document is what will be provided to anyone wishing to see proof of the organization’s tax exemption.