Iowa doesn't accept Form IA 1040X, Amended Individual Income Tax Return, via e-file.
You do have the option to use the appropriate-year IA 1040 with the word "Amended" written at the top.
According to Iowa’s Amending Tax Returns page,
Attach the federal 1040X, if one was filed, and any amended supplementary federal or Iowa forms. If you amend on an IA 1040 form, also attach an IA 102 Amended Return Schedule.
Print and mail your return to:
Income Tax Document Processing
Iowa Department of Revenue
PO Box 9187
Des Moines IA 50306-9187
Please note that the Iowa Department of Revenue has extended the filing and payment deadline to June 1, 2021 for 2020 individual income tax returns.
