The Sarbanes-Oxley Act: Overview and Implementation Procedures Manual

It is the sense of the Senate that the Federal income tax return of a corporation should be signed by the chief executive officer of such corporation.
Since the CEO will sign the return it follows that he/she must be fully cognizant of its content and accuracy. Since these returns are often complex, a CEO is going to have a lot of confidence and trust in his/her CFO. Otherwise, it may be desirable to have a third party evaluate the return on behalf of the CEO before he/she signs it.