Can an employee retire at some time other than after the school calendar ends and before the next school calendar begins?
Yes.
An employee can notify the board anytime in the fiscal year in which the employee will retire as long as that notification is before April 1 of that same school year. In other words, the notification can be any day on or after July 1 but before April 1. The date of the employee's retirement can be any day in that same fiscal year after the notification to the board as long as it is no later than the first day of the following school calendar. In other words, the retirement can be any any day on or after July 1 of the fiscal year but no later than the day before the teaching contracts begin for the next school year -- a retirement window of approximately 14 months.