If a parent desires to be credited with timeshare hours when they are not physically with the child, then that parent has the burden of providing admissible evidence that they have primary physical responsibility of the child during the time at issue.
After a divorce proceeding, mother and father shared custody of their son, Justin, and were both jointly responsible for dropping him off and picking him up from school. However, there was no evidence as to which parent was responsible for Justin during school hours. 1260 hours were at issue, translating into approximately 52 days of time that was not allocated to either parent for child support purposes. In determining the child support obligations of each parent, the divorce court originally determined that the father timeshare was 42% but then subsequently changed the timeshare amount to 29.1% after reconsidering the issue on its own motion. The father’s divorce lawyer argued that the court had incorrectly reconsidered the timeshare based on an erroneous interpretation of a recently published opinion, In re Marriage of Rosen (2002) 105 Cal. App 4th 808.
In determining child support, the timeshare calculation is a part of the equation used by divorce courts to calculate the “approximate percentage of time that the high earner has or will have physical responsibility of the child  compared to the other parent.” The divorce court decided the way to calculate the timeshare was not changed by Rosen. Additionally, the divorce court had to calculate the percentage of time the father has or will have “primary physical responsibility” of their son. The “primary physical responsibility” is calculated by determining the amount of time each parent has primary physical responsibility of the child, and not necessarily physical custody.
If a parent wants credit for a portion of time where the child is not physically with them, then that parent has the burden of showing they are primarily responsible for the child during the disputed time frame. In making such determinations courts should consider: “(1) who pays for transportation or who transports the child; (2) who is designated to respond to medical or other emergencies; (3) who is responsible for paying tuition (if any) or incidental school expenses; and (4) who participates in school activities, fundraisers, or other school –related functions.” The Appellate Court found, the divorce court had made a mistake by solely calculating the timeshare factor only on the father’s physical custody of the son therefore concluding that Rosen had not altered the vast body of case law interpreting the timeshare factor. Further, the father should have been credited at least a portion of time the son spent in school. Thus, the timeshare allocations have to be recalculated.
DaSilva v. Dasilva, 119 Cal. App. 4th 1030 (2004)