Department announces 2016 interest rates, standard deduction, & tax brackets. Having trouble viewing this email? View it as a Web page. Department announces 2016 interest rates, standard deduction, & tax brackets. Department announces 2016 interest rates, standard deduction, & tax brackets. For details: https://tax.iowa.gov/press-release/iowa-department-revenue-announces-interest-rates-standard-deduction-amounts-and-tax