When parents share parenting time equally (50/50), one of the two parents must have at least one more overnight than the other because there are an odd number of days in a year (365). In most cases, one parent will have 183 overnights and the other will have 182 overnights.
The Custody Ratio Tiebreaker Under these rules, the parent who has physical custody of the child for the greater part of the year – defined as more than 50% of the nights – typically has the right to claim the child as a dependent for tax purposes.
The guideline states that the paying spouse's support be presumptively 40% of his or her net monthly income, reduced by one-half of the receiving spouse's net monthly income. If child support is an issue, spousal support is calculated after child support is calculated.
40% of the high earner's net monthly income minus 50% of the low earner's net monthly income. For instance, if Spouse A earns $5,000 per month and Spouse B earns $2,500 per month, temporary spousal support might be calculated as follows: 40% of $5,000 = $2,000. 50% of $2,500 = $1,250.
The type of custody you have (joint or sole) has no effect on child support. Parenting time can have an effect on child support with a reduction to the payor for having over 30% of the time. This is based on the old standard of parenting time with a ``custodial'' and ``non-custodial'' parent.
In California divorces where both parents share 50/50 custody of a child or children, child support payments generally amount to 15% of the difference between the parents' earnings. Other factors (like the number of children you share, your monthly incomes, etc.) also factor into the decision.