Husband appeals from a judgment that terminated his spousal support obligation based on a substantial change of circumstances and that also required him to pay a retroactive child support obligation of $6,300. The trial court imposed the retroactive support obligation sua sponte without wife requesting such relief by way of any appropriate motion or pleading. We agree with husband that, in the circumstances presented here, the court’s sua sponte imposition of the retroactive support obligation was erroneous. See Richards and Richards, 95 Or App 281, 284, 768 P2d 927 (1989) (in the absence of a motion to modify, a retroactive support obligation could not be imposed on a prior custodial parent following a change of physical custody).

Imposition of child support arrearage obligation of $6,300 reversed; otherwise affirmed.