Which corporations are required to file returns electronically?
Per the IRS:
"Temporary Regulations issued January 11, 2005 and Final Regulations announced in TD 9363, which were implemented effective November 13, 2007, require certain corporations to electronically file. Those corporations with $10 million or more in total assets and that file 250 or more returns a year are required to electronically file their Form 1120, 1120S, and 1120-F."
Please see the IRS website for E-file for Large Business and International (LB&I) for additional information.