Iowa Code § 97B.45: Normal retirement date.

A member’s normal retirement date is any of the following, whichever is applicable to the member:

1. The first of the month in which a member attains the age of sixty-five years if the member has not completed twenty years of membership service.

2. The first of the month in which the member attains the age of sixty-two years if the member has completed twenty years of membership service.

3. The first of any month in which the member has completed twenty years of membership service if the member has attained the age of sixty-two years but is not yet sixty-five years of age.

4. The first of any month in which the member is at least fifty-five years of age and for which the sum of the number of years of membership service and prior service and the member’s age in years as of the member’s last birthday equals or exceeds eighty-eight.