Iowa Admin. Code r. 701-38.12
Effective for tax years beginning on or after January 1, 1990, the optional standard deduction is indexed or increased by the cumulative standard deduction factor computed by the department of revenue. The cumulative standard deduction factor is the product of the annual standard deduction factor for the 1989 calendar year and all standard deduction factors for subsequent annual calendar years. The annual standard deduction factor is an index, to be determined by the department of revenue by October 15 of the calendar year, which reflects the purchasing power of the dollar as a result of inflation during the fiscal year ending in that calendar year preceding the calendar year for which the annual standard deduction factor is to apply. For tax years beginning on or after January 1, 1996, the department shall use the annual percentage change, but not less than 0 percent, in the gross domestic product price deflator computed for the second quarter of the calendar year by the Bureau of Economic Analysis of the United States Department of commerce and shall add all of that percentage change to 100 percent, rounded to the nearest one-tenth of 1 percent. The annual standard deduction factor shall not be less than 100 percent.
This rule is intended to implement Iowa Code section 4224..
Iowa Admin. Code r. 701-38.12