The issue raised on this appeal by Jeffrey Batts (former husband) is whether there was competent evidence from which the trial court could have concluded that a substantial change of circumstances had occurred in order to support an increase in child support. Based on our reading of sections 61.13 and 61.14(1), Florida Statutes (1989), we agree with the trial court that there was competent substantial evidence establishing a substantial change in circumstances.

As to the issues raised by the former wife on cross-appeal, we reverse. In calculating a modified child support amount, the trial court incorrectly allowed a deduction from the former husband’s gross income which represented the amount he was currently paying in child support. This contravenes section 61.-30(3)(f), Florida Statutes (1989). Additionally, an increased award of child support should be made retroactive to the time when a petition for modification of a domestic judgment of dissolution is filed.

AFFIRMED IN PART; REVERSED IN PART; REMANDED.