Where no benefit accrued to the custodial parent by the noncustodial parent's action of reducing the received child support, and it could not be concluded that the payor's actions were the result of apparent or implied authority or that there was a principal and agent relationship between the parties, consequently, the legal concept of ratification was misapplied.

This section guarantees the dependent minor child of divorced parents from loss of support through disinheritance; while a divorced parent is free to disinherit a child of his divorced marriage, he may do so only subject to the limited obligation of support. The paramount concern in child support litigation is the support of the minor children. In a modification proceeding, the fact that at least a part of a trial court's reasoning consisted of the assumption that the parties knew what they were getting into was not a valid basis for affirming a divorce agreement which provided for no child support.

Accounting

Since it was within the trial court's discretion, due to fluctuations in husband's income, to order respondent husband to submit a quarterly accounting of his net income to petitioner wife, the child support order was modified to require an annual accounting.

Arrearages

Where the testimony of the plaintiff and defendant was directly in conflict with respect to the extent with which defendant had met his child support obligation to spend an additional $15 per month per child, the trial court had the responsibility of resolving this conflict and to determine the credibility of witnesses; the finding of the trial court under such conditions should be approved unless it is found to be contrary to the manifest weight of the evidence. Past-due installments of child support are a vested right, and the court has no authority to modify them, either as to amount or time of payment.

Burden of Proof

A trial court may, on application, terminate or make such alterations in the allowance of child support, as shall appear reasonable and proper and the burden of proof is on the person seeking modification to show such material change in circumstances as would warrant modification.

Calculation

Per diem payments made to the husband, an over-the-road truck driver, constituted income for the purpose of calculating child support but could be deducted from income to the extent the husband proved he used those payments for actual travel expenses, but the husband had the burden of proving his actual expenses and of establishing a lawful basis for deducting them. Because the language "$30.00 child support" was susceptible of being understood as ordering respondent to make either a lump sum payment in the amount of $30 or periodic payments in $30 increments, and the record did not justify an interpretation of $30 per week child support, the award calculated on the basis of that interpretation was improper.