Unable to e-file Form 1120X Amended returns Customer Support Updated September 24, 2022 21:11 According to IRS instructions: File this form at the applicable Internal Revenue Service Center where the corporation filed its original return. This information applies to all years of the UltimateTax software. Related articles 1120X - Amend Income Tax Return CA100S 1120S line 22 not calculating Entering capital gain distributions 2019 Modules and Updates