Iowa Code § 731.5: Deducting dues from pay unlawful.

It shall be unlawful for any person, firm, association, labor organization or corporation to deduct labor organization dues, charges, fees, contributions, fines or assessments from an employee’s earnings, wages or compensation, unless the employer has first been presented with an individual written order therefor signed by the employee, which written order shall be terminable at any time by the employee giving at least thirty days’ written notice of such termination to the employer.