You can right now if you want to on paper. Additionally, if you owe any state taxes on the original return and are able to pay the amount due, you might want to consider doing that to save some tax due notice headaches down the road. But if you are not able to pay, make sure and have the amended return in before 4/30. TurboTax will not have the amend option ready until mid to late March. Here is a link to information on amending your Iowa return on paper.
