Iowa doesn't have any specific laws or regulations when compared to other states in the U.S. The federal rules and principles governing 1031 exchanges across all states are applicable for Iowa as well.
Iowa allows taxpayers to deduct federal income taxes from their state taxable income. The Combined Rate accounts for Federal, State and Local tax rates on capital gains income, the 3.8 percent Surtax on capital gains and the marginal effect of Pease Limitations (which results in a tax rate increase of 1.18 percent).
Iowa allows for a deduction of all federal taxes actually paid in cash during the year. The deduction is equal to federal taxes withheld from paychecks during the year, plus any estimated payments made during the year, plus any federal taxes paid with the taxpayer's tax return during the year. Note that this means the taxpayer would be deducting taxes paid with prior year federal return since that return would have been filed during the current calendar year. Iowa allows for a Tax Credit instead of a deduction for taxes paid in other states.