Iowa Code § 275.56: Increasing enrollment.

If the enrollment of a school district increases or is expected to increase because an adjacent district has dissolved or is expected to dissolve, the board of directors of the school district shall determine whether there is a need to hire additional licensed or unlicensed employees. If the board of directors determines that there is a need to hire additional employees, the board shall determine the nature and number of the necessary new positions. Individuals who were employees of the dissolved district may apply for the new positions. The board shall hire those applicants who were employees of the dissolved district whenever the applicant is licensed for the new position or, in the case of unlicensed personnel, is otherwise qualified. If two employees of the dissolved district apply for a single licensed position, the applicant who is best qualified in the opinion of the board shall be hired. The board is not required to hire applicants who were employees of the dissolved district if the district has been dissolved for one or more school years. Applicants who are reemployed under this section shall maintain in the reemploying district vacation, salary or alternatively placement on a salary schedule based on the employee’s years of experience, sick leave, and completion of probationary status as defined by section 279.19.