How do you change corporation status from C corporation to a S corporation?

The shareholders would make an election by filing a form 2553 with the IRS. For an existing corporation, the form must be filed by March 15 of the year the election is to be effective. The election would then begin from January 1 of the year the election was made.

Word of Caution - there can be adverse tax consequence for the corporation and the shareholders if an election is made without consulting a tax advisor.