S Corporation Election Form 2553 must be filed no later than 15th day of third month for year election is to be effective A new corporations tax year begins on first day it acquires assets, has shareholders or begins business All shareholder must consent to election 66 S Corporation Election Form 2553 must be filed no later than 15th day of third month for year election is to be effective –A new corporation’s tax year begins on first day it acquires assets, has shareholders or begins business All shareholder must consent to election