Iowa Code § 91A.4
When the employment of an employee is suspended or terminated, the employer shall pay all wages earned, less any lawful deductions specified in section 91A.5 by the employee up to the time of the suspension or termination not later than the next regular payday for the pay period in which the wages were earned as provided in section 91A.3. However, if any of these wages are the difference between a credit paid against wages determined on a commission basis and the wages actually earned on a commission basis, the employer shall pay the difference not more than thirty days after the date of suspension or termination. If vacations are due an employee under an agreement with the employer or a policy of the employer establishing pro rata vacation accrued, the increment shall be in proportion to the fraction of the year which the employee was actually employed.
Iowa Code § 91A.4