https://www.irs.gov/instructions/i1120s#en_US_2024_publink11515kd0e1133
Amended Return
To correct a previously filed Form 1120-S, file an amended Form 1120-S and check box H(4) on page 1. Attach a statement that identifies the line number of each amended item, the corrected amount or treatment of the item, and an explanation of the reasons for each change.
