James Morgan’s child-support obligation was reduced after the trial court found that he had suffered a substantial involuntary loss of income in his construction business. The court reduced his monthly obligation from $632 to $223, but refused to apply the reduction retroactively to the date Morgan served his modification petition. It also calculated arrears and held Morgan in contempt. The Georgia Court of Appeals held that the trial court had applied Galvin v. Galvin too broadly in the contempt proceeding. Under OCGA § 19-6-15(j), when a parent suffers qualifying involuntary adversity, the portion of support attributable to lost income does not accrue after the modification petition is served on the other parent. The statute does not make the modification order itself retroactive, but it does govern the later calculation of past-due support. Because the trial court had not determined what portion of Morgan’s arrearage was attributable to involuntarily lost income during the period between service and the modification order, the Court of Appeals vacated the order and judgment and remanded for that calculation. Judge McFadden concurred in the judgment only and suggested the Supreme Court should reconsider the issue; that posture made the decision nonbinding under the Court of Appeals’ rules.