A judge makes an order for child support. But it later turns out that the child is not living with the parent to whom the child support is supposed to be paid. Is that fair? Is there anything a court can do, or does it even matter?

The answers to some of these questions were provided in the recent California Court of Appeal case entitled Marriage of Wilson. In Wilson, the dad (“Michael”) faced arrears of $7,006.19, not including interest. However, there was “undisputed evidence that during most of the time between 1981 and 1987, Michael’s own parents cared for the parties’ child in the grandparents’ home. During that time, Michael provided money to his parents for the child’s care. During that same time, the mother did not provide any support for the child.

In analyzing this situation, the Court of Appeal noted that California law already provided for relief from arrears when the obligor parent shows that he or she cared for the child at the parent’s own expense. In other words, if a mother has custody but the child actually lives with the father, the father is often relieved from the obligation of child support during those months when the child lived with him. (Often what happens is that the child custody order provides for the child to live with the mother but the father ends up caring for the child, or, of course, the other way around.)

What the Court of appeal did in Wilson was extend this doctrine, often called the “equitable setoff” doctrine, to those situations where the obligor does not provide for the minor in her or his own home. To do otherwise, the Court of Appeal reasoned, would give the mother a windfall in cash even though the child was not living with her and she was not providing for her support.

As a result of the Court of Appeal’s decision, the matter was sent back –“remanded”– to the trial court to recalculate the arrears that the father should have to be paid.

A complicated situation like this can be avoided if a motion to modify child support is filed when the change in living situation occurs. In Wilson, however, the case was complicated because the child was born back in 1979, and there were hearings about the strange circumstances in 1985, 1987, 2000, and finally 2012.

The Wilson case reversed a trial court’s decision made up in Alameda County. However, because Wilson was cited for publication, it is binding precedent on trial courts throughout Californa, including San Diego. The vote in Wilson, by the way, was unanimous; all three justices agreed.

One final observation: keeping track of child support payments is very important, both for the payor and the recipient. The obligor should never pay child support in cash unless a receipt is provided. If child support is garnished, as the law provides, the paystubs reflecting the garnishment should be kept. In any event, failure to pay child support is costly. The interest accumulates at the rate of 10 percent per annum.