Baxter

*347 Eleven retired teachers (Teachers) who had been employed in the Salinas Unified High School District (District), disputed attempts by appellant California State Teachers' Retirement System (CalSTRS) to recoup retirement benefit overpayments. The overpayments were the result of a years-long miscalculation by the District of the monthly retirement benefits to which the Teachers were entitled. The parties do not dispute that the District miscalculated Teachers' monthly benefit amounts. But Teachers contend that the statute of limitations bars CalSTRS's efforts to recoup prior overpayments and to reduce future monthly benefits to the proper amounts.

The dispute stems back to 1999, when the District and the Teachers' union entered into a collective bargaining agreement that purported to create a separate class of employees for teachers who elected to work an extra (sixth) period. Some years later-on August 18, 2005, after three Teachers had retired-a District employee sent a memorandum to the Monterey County Office of Education (MCOE), which arguably alerted MCOE to the potential overpayment of retirement benefits to teachers in the District who had worked a sixth period. In…