A proposal advancing in the Iowa Senate would amend the Iowa constitution to make it more difficult to raise INCOME taxes. The amendment would require any income tax increase to be approved by a two-thirds supermajority in the House and Senate. Republican Senator Jim Carlin of Sioux City says the requirement would help Iowa be more competitive with South Dakota, which does not have a state income tax.

In 1999, Iowa voters rejected a constitutional amendment that would have limited state spending. In 2010, Iowa voters approved an amendment setting up a new state water conservation and outdoor recreation fund, to be filled the next time the sales tax is raised.