Yes and No. In Iowa, you must be a member of a political party (currently: Republican and Democratic) to vote in a primary election. However, anyone* can change parties on Election Day and vote. For independents to vote they must declare a political party.

*Precinct election officials may not change political parties within 30 days of an election.

Iowa does not recognize an “independent” party. Instead, “No Party” is used to indicate a lack of affiliation with a political party.