For better or worse IRS does contradict itself. M-Mtax is right that 2024 instruction for form 1120-S say in plain English that you have to e-file if you have more than 10 tax filings. OK. Down that document it DOES say that to amend a return file A PAPER copy.
For returns filed on or after January 1, 2024, S corporations are required to e-file Form 1120-S if they file 10 or more returns of any type during the calendar year (including income tax, employment tax, excise tax, and information returns).
Down these guidelines for 2024 it says:
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.
https://www.irs.gov/instructions/i1120s#en_US_2024_publink11515kd0e1133
The only confusion is with a separate guidelines (@rleaf) that say persons should amend returns in the same manner they filed original one.
