You should file the Form 1120S because this can no longer be reported directly on your tax return. The IRS will be looking for the return, regardless of the inactivity. If there was no income or deductions you can simply enter zero.
S corporations must file a summary of information regarding income, deductions, credits, and other items that pass through to the corporation's shareholders. You provide this summary to the IRS through Schedule K,Shareholders' Pro Rata Share Items. You include Schedule K when you file Form 1120S, then the Schedule K-1 is used by the shareholder to report the information on their personal return.
