Legal Question in Family Law in California

No, only your income is included. The calculation is based, however, on "disposable" income as that is calculated by the DissoMaster program. It is close to but not identical to "after-tax" income. Because being married to an earner impacts how much tax you pay on your income, it indirectly affects support. By the way, your son does not decide where he wants to live unless you and your ex decide to let him. Otherwise the determination is what is in the best interests of the child. If you have 100% custody, there must be something in the history of this family that would call into doubt whether turning custody over to her would be in the best interests of the child.