Form 1120-S is supported by TurboTax Business for Desktop, which is a different program from TurboTax for Desktop (Deluxe, Premier, or Home & Business). To change/amend an 1120-S that has already been filed, create and file a new 1120-S with all necessary changes. There is not a separate form for this purpose.
Per the IRS Instructions for Form 1120-S: 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.
If you e-filed your original 1120-S return with TurboTax Business, you won't be able to e-file an amended 1120-S. In this case, you'll need to print and mail the new return.
See also: What is Form 1120-S, U.S. Return of an S-Corporation?
[edited 1/18/2016 | 1:38 PDT]
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