According to the Internal Revenue Service code, institutions operating exclusively for educational purposes qualify for exemption from federal income taxes.
The code states that an educational institution is still considered educational even if it advocates a particular viewpoint as long as it “presents a sufficiently full and fair exposition of the pertinent facts.” An institution is only considered not to be educational if its “principal function” is the “presentation of unsupported opinion.”
A tax-exempt organization is also permitted to attempt to influence legislation, so long as that doesn’t represent a “substantial” part of its activities.