DES MOINES, Iowa (AP) – The Iowa Department of Education says it will stop granting automatic waivers to school districts seeking to start classes earlier in the summer. Department director Brad Buck sent a letter Friday to state education leaders saying the change is effective immediately.

The announcement came shortly after Gov. Terry Branstad sent a letter to Buck asking that officials only grant a waiver if a school district demonstrates a “significant negative educational impact” of beginning classes on time, as required by law.

Districts must start school no earlier than the calendar week that includes Sept. 1. But nearly all of them obtain waivers allowing them to begin classes earlier. Branstad’s letter says starting earlier “unnecessarily interferes” with families’ summer plans, seasonal hiring and the Iowa State Fair.