Can child support be retroactively modified in Florida?

When either parent requests that child support be modified, that request can be applied going back to the date that they requested the support be modified. The only exception to that is if there had been a parenting plan in place and one of the parents failed to exercise all of the time that they had been given under that parenting plan. Then the parent that had all the extra time can ask that child support be modified going back to the time that the parent failed to exercise the time that had been given to them under the parenting plan. Other than that exception, it can only be modified going to the date that the request to be modified started.