Neither child nor spousal support is taxable income nor tax deductible income for any agreements and/or orders after January 1, 2019. Prior orders and agreements entered 2018 and earlier retain tax deductiblity for the payor and taxable income to the recipient as to spousal support only. Child support is never taxable income nor tax deductible.
You can avoid physically going to court if you reach an agreement outside of Court; but the paperwork must be submitted to Court before the order can be enforced. The orders for support can be changed whenever there is a material change of circumstances or whenever the parties agree and reduce the agreement to a written stipulation that is signed by the Judge as an order.
Child support and (for most judicial officers) temporary spousal support is calculated by using a specific calculator approved by the Judicial Council. Child support continues until the child is 18 or is a full-time high-school student until aged 19. Temporary spousal support (alimony) is from after you file a motion after the Petition for Dissolution is filed until the trial/Judgment. Temporary support is designed to be higher than the support after judgment. At trial there are a myriad of factors that must be considered under Family Code 4320 but the two biggest are the recipient's need and the payor's ability to pay. It is a misconception in most cases to continue the status quo since the same income must support two households that formerly supported one. It is impossible for both households to maintain the status quo. There are many other factors that enter into the support under FC 4320. Another consideration is the length of the marriage. A marriage of 10 years or longer is presumed to be a long-term marriage. Support is usually paid 1/2 the length of the marriage (from date of marriage to date of separation) for short-term marriages. Termination of support for long-term marriages depends on many factors, including the ability of the recipient to become self supporting. Usually the marriage of the recipient or death of either party terminates support.
If a party voluntarily leaves a higher paying job, the Judge has the ability to impute the income that was previously earned to the spouse who voluntarily left. "Impute" means pretend the spouse is still working at the previous job and determine support using that pretend income.
This depends on many factors. If this is child support (or even spousal support to a degree), the judicial officer will look at the best interests of the children for the spouse to work outside the home. If this is spousal support, there is a warning that should be given to the recipient spouse that the law requires that spouse to become self supporting in a reasonable time. Sometimes vocational experts can be retained to assess whether the recipient spouse has skills and opportunity to earn more income (or any income). This usually costs $2,500-$5,000 but over time may pay for itself. The Court may impute the earnings found by the expert as "pretend" earnings to the recipient spouse. Very often the Court will impute minimum wage to either spouse unless there is a physical or mental impairment.
Support orders are collected as any other judgment. There is a code section that allows for a % of costs and fees to be collected from the payor spouse (who is not paying). 10% interest per annum attaches to unpaid support. DCSS will confiscate tax refunds and has the ability to request the Court to suspend professional and driver's licenses. A wage assignment can issue and usually does.