If the obligor fails to demonstrate his or her income during the retroactive period, the Court shall apply the current child support guidelines to calculate retroactive child support payments. “In addition, the ALJ erred in using Finch’s current monthly income to compute the retroactive support obligation. The use of current income is permissible when the obligor fails to demonstrate his or her actual income during the retroactive period. See § 61.30(17)(a), Fla. Stat. (2011) (providing that the ‘[f]ailure of the obligor to… demonstrate [his or her actual income] shall result in the court using the obligor’s income at the time of the hearing in computing child support for the retroactive period’).” Finch v. Dep’t of Revenue o/b/o John-Jules