Can child support be retroactively modified in Florida?

Generally, child support cannot be modified retroactively in Florida. There is an exception, however, where a parent is ordered to pay child support based upon a time-sharing schedule, and that parent has voluntarily failed to exercise their parenting time. The recipient of the child support can petition for a modification of child support, retroactive to when the paying parent stopped exercising the parenting time based on the time-sharing schedule and ask for a modification or increase as a consequence of the parent failing to exercise their parenting time.