## The Duty

The statutory obligation for parental support of minor children is found in several locations in the Code. Generally, however, Family Code sections 3900 et seq. describe the general obligation of both parents to support their child "in the manner suitable to the child's circumstances." This duty extends to all minor children of the parents, whether legitimate or illegitimate, natural or adopted. This obligation to support a child is not dependent upon the existence of a valid marriage. Further, one might interpret Family Code section 3900 as being restricted in scope to "minor children." This reading is not, however, correct, although when speaking of the concept of child support in the family law context, the focus is almost always on the support of minor children.## Getting to Net Income

Calculation of child support requires us to get from Gross income to Net income, since the formula uses net income. Gross and net disposable income are also defined in the Code at sections 4058 and 4059, respectively, which addresses these concepts as they relate to child support calculations. Conceptually, they provide that gross income includes income (as that term is generally construed by the IRS) from all sources, and net disposable income is gross income less all allowable deductions (usually state and federal taxes, union dues, mandatory retirement benefits, health insurance deductions, and items of a similar nature). This is the area where a lot of people try to "fudge" on their income. For most wage-earners, however (people paid with W-2's), the information is readily available on their paychecks.## The Formula

The formula for the calculation of guideline child support is contained in Family Code section 4055. That formula is expressed as follows: CS = K [HN - (H%)(TN)]. In this formula, the symbols set forth below (and used in the formula) make reference to the following definitions:

CS = child support amount

K = amount of both parents' income to be allocated for child support

HN = high earner's net monthly disposable income

H% = higher earner's approximate time of physical responsibility for the children

TN = the parties' total monthly net income

This formula will produce an amount of support per minor child. When more than one child is involved, the end result (CS) is then multiplied by a specific factor depending upon the number of children. For example, for two children the multiplier is 1.6; for three children, the multiplier is 2; for four children the multiplier is 2.3; for five children the multiplier is 2.5; for six children the multiplier is 2.625, and so on.## The K Factor

The K factor is defined in subsection (b)(3) of section 4055 as being a function of the amount of time the high earner spends with the child(ren) multiplied by a statutorily determined fraction. If the high earner spends 50 percent or less time with the children, then the multiplier is calculated one way, and if the amount of time is greater than 50 percent, then the multiplier is calculated another way. If the percentage of time is 50 or less, the multiplier is equal to one plus that percentage. For example, if the amount of time is equal to 20 percent, then the multiplier is equal to 20 percent plus 1, or .20 + 1 = 1.20. If the amount of time is equal to 85 percent, then the multiplier is equal to 85 percent subtracted from 2, or 2 - .85 = 1.15.## What this Means

As should be evident, the more time the high earner spends with the children, the lower the multiplier will be, which will have the effect of lowering the guideline amount of child support. This result is due to the statutorily recognized (and common-sense) conclusion that the more time the children spend with the high earner, the more it will cost to provide the day-to-day needs of those children, and the less it will cost the other parent (since she doesn't have the children as much).## How it Works

Once the K factor is determined, the rest is simply plugging numbers into the formula. Let us assume, then, that the high earner's net monthly disposable income is $8,000 and the other party's net monthly income is $2,500. The high earner also has primary responsibility over the minor child 20 percent of the time. Based on these facts, the K factor equals (1 + 0.20) x (0.10 + [1000/10,500]), or, 1.20 x .195 = .234.

Plugging this number into the formula yields the following result:

CS = K[HN - (H%)(TN)]

CS = .234 [8500 - (.20)(10,500)]

CS = .234 [8500 - 2100]

CS = .234 x 6400 = $1,497.60

The guideline child support award under these facts is thus $1,497.60 per month, which the high earner will pay to the low earner.## What If There Is More Than One Child?

Section 4055(b)(4) establishes a chart of multipliers to be employed when there is more than one child. The multiplication factor for four children is 2.3. To arrive at the appropriate amount of child support we merely multiply the result obtained for one child ($1,497.60) by 2.3 to arrive at a monthly child support award, for four children, of $3,444.48.## How Is Support Allocated Among Several Children?

We need to allocate this $3,444.48 amount among the four children, providing a specific dollar amount for each. Section 4055(b)(8) instructs that this is accomplished by allocating at least the amount of support allocable to one child (under these circumstances $1,497.60) to the youngest child, with the next youngest being allocated the difference between that amount and the amount allocated for two children. In this case, the amount allocated for just two children would have been $2,396.16, so this "next youngest" child is allocated $898.56 of the $3,444.48. The remaining two children are allocated a support amount in a similar fashion: child number 2 receives the difference between $2,396.16 (two children) and $2,995.20 (three children), or $599.04. The oldest child is thus left with an allocation of $449.28. The total child support award of $3,444.48 is thus allocated among these children as shown below:## The Allocation

The total child support award of $3,444.48 is thus allocated among these children as follows:

youngest child: $1,497.60

next youngest: 898.56

third youngest: 599.04

oldest child: 449.28

By allocating the child support in this manner, it ensures that the highest portion of the support is allocated to the youngest child. By so doing, as the older children reach the age of majority and no longer receive child support payments, not only will the parties know by how much the award will drop, but the drop-off will be the lowest possible amount, thus ensuring that the remaining children continue to receive the amount required by the guidelines.## The Alternative to Doing it Yourself

OK. Now you see how you can manually calculate child support in California using its statutory guideline. There is, of course, an easier alternative: there are several child support calculators available online, usually for free. They are typically not as accurate as this, but they will give you a good starting point. You should consult with an experienced family law attorney with any questions you have on this topic. Good luck!

Filed under: Child support Finances and child support Determining child support payments Family law Tax law

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