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Guide to the complex calculation of child support under California guidelines

In California, a complex calculation is used to determine child support payments. This calculation looks at each parents’ incomes, time spent with the children, and tax deductions that either parent can take. This formula comes into play when a minor child requires a support determination, generally in cases of divorce, paternity and domestic partnership situations.

When calculating child support in California, all courts and judges use the same child support calculation. Due to the complexity of the child support formula, a computer program called the Dissomaster is used to calculate the monthly child support amount. The calculation contains accurate and honest information submitted by each spouse. It is particularly important to hire an experienced and skilled family law attorney at Minella Law Group to help you negotiate certain terms to be included in the calculation to ensure you receive the correct amount of child support.

Purposes for the guideline

The guideline has two purposes: (1) it provides for a minimum level of child support for a child; and (2) it provides for a uniform calculation of child support. In order to achieve these purposes, California requires that the guideline be followed by judges and only allows deviations in certain special circumstances.

Underlying principles

There are certain principles for creating the child support guidelines:

  • The most important obligation of a parent is to provide financial support for his or her child consistent with each parent’s situation and station in life.
  • Each parent has a responsibility to support their children financially.
  • The child support guideline is generally correct in all cases. Only in certain circumstances should a child support order go below the guideline formula.
  • Child support orders should reflect California’s high costs and accordingly high standard of living to ensure each child receives fair, timely and adequate support.

Guideline application

The guideline is a pretty complex algebraic formula that requires each parents’ income, deductions, and time spent with the child. The items each parent should have for child support to be calculated by the Dissomaster include:

  • Most recent tax returns
  • Paycheck stubs
  • W2s or 1099s
  • Any unemployment or disability benefits information
  • Child care expense information
  • Any extraordinary health care expenses and health insurance information
  • Any retirement contributions that are mandatory
  • Necessary job-related expenses not reimbursable by an employer
  • Any spousal support paid from other relationships
  • Any catastrophic losses that are uninsured
  • Child support for other children

Once information from these sources are plugged into the calculator, it generates a monthly child support amount.

The formula

The following is the complicated formula used to calculate child support in California:
CS = K (HN – (H%) (TN))

  • “CS” stands for child support. This will represent the amount when all information is included which reflects an amount for one child only. If the parents have more children, the amount must be multiplied by a number set out in the law.
  • “K” is the combined parent’s income to be allocated for child support. This amount is dependent upon earnings by each parent and percentage of time the high-earning parent spends with the child.
  • “HN” represents high net: the monthly net disposable income of the parent with the higher income.
  • “H%” is the approximate percentage of time the high-earning parent has versus the other parent. (i.e., the higher-earning parent may have 25% of parenting time while the other parent has 75%).
  • “TN” represents the total net monthly disposable income of each parent combined.
    The greater the difference in incomes between the two parents’ and the lesser amount of time the principal earner spends with the children, the more they will have to pay in child support.

Deviations from the child support guideline

Under the California Family Code, the guideline amount of child support is “presumed to be the correct amount of child support to be ordered.” Thus, a judge must comply with the guideline amount of child support, unless there are special circumstances as to why it must be different.

There may be situations when application of the guideline would be unfair or unreasonable. These situations include:

  • The parent ordered to pay child support has a very high income and the child support amount calculated would exceed the children’s needs.
  • A parent should be contributing for the children commensurate with the custodial time of that parent.
  • Where both parents have equal parenting time and one parent has an income that is much higher or lower than the other parent, where such income is used for housing.
  • Special medical care or needs should be taken into account, or there are greater needs of the children that require more child support than the formula allows.

Add-ons for child support

There are two types of child support add-ons in addition to the child support amount calculated from the required guideline:

Mandatory add-ons. The judge must order the following added to child support: (1) employment-related child care costs or cost for reasonable training/education skills for employment; and (2) reasonable costs of health care.

Discretionary add-ons: It can also be ordered that a parent contribute to: (1) educational costs or other special needs of the children; and (2) travel-related expenses for visitation (generally incurred by the custodial parent).

If these add-ons are ordered by the judge, the expenses are required to be shared equally by both parents, unless equal allocation is unreasonable. In that case a judge may make each parent pay in proportion to their net spendable incomes.

Minella Law Group to assist with a child support order modification

Our Child Support Lawyers at Minella Law Group will work to secure your best interest in calculating and negotiating the amount of child support you will pay or receive. Determining child support can be quite complex and difficult, but it is so critical in ensuring the stability of you and your family. Our Family Law Attorneys will support you and work to protect your personal, financial and family well-being through diligent investigation, careful analysis, and experienced advocacy.


For more information or to schedule an appointment, click below or call us at (619) 289-7948. We look forward to helping you.