Who Must File
Form 1125-E must be completed and attached to Form 1120, 1120-C, 1120-F, 1120-RIC, 1120-REIT, or 1120S, if the entity has total receipts (defined below) of $500,000 or more, and deducts compensation for officers.
See https://www.irs.gov/instructions/i1125e#idm140008514373824
