Kansas Child Support Calculation: Income Shares Model Explained

Kansas child support isn't a flat percentage of one parent's income. The state uses the Income Shares Model, which estimates what both parents would have spent on the child if the household had stayed intact, then divides that obligation proportionally based on each parent's earnings. The calculation is more involved than most parents expect, and the details matter — a parenting-time shift of one overnight per week can change the number by hundreds of dollars per month.

Step 1: Determine Each Parent's Support Income

Both parents report their gross domestic income: wages, salaries, bonuses, commissions, self-employment earnings, investment income, and other regular sources. The guidelines cast a wide net — tips, overtime, and rental income all count.

When reporting support income, include all regular sources rather than assuming only wages matter.

Step 2: Calculate Proportionate Shares

Add both parents' incomes together. Each parent's share of the total becomes their proportionate percentage.

For example: Parent A earns $6,000 per month and Parent B earns $4,000. Combined income is $10,000. Parent A's share is 60%, Parent B's is 40%. Those percentages drive everything that follows.

Step 3: Find the Basic Obligation Using Age Brackets

Kansas child support schedules use three age brackets that reflect the increasing cost of raising children:

• 0 to 5 years — lower base obligation
• 6 to 11 years — moderate base obligation
• 12 to 18 years — highest base obligation

Using the combined income and the child's age bracket, the court looks up the basic child support obligation on the published schedule table. Each parent's proportionate share of that obligation determines their initial contribution.

Step 4: Add Mandatory Costs

The basic obligation doesn't cover everything. Actual, reasonable health, dental, and vision insurance premiums for the child, along with work-related childcare costs, must be added and shared proportionally:

• Health insurance premiums — the cost of adding the child to a parent's employer plan or individual policy
• Work-related childcare — daycare, before/after-school care, or summer programs necessary for the parent to work The parent who pays these costs directly receives a credit on their support worksheet.

The parenting plan must specify how unreimbursed medical, dental, or therapeutic costs are divided; they are typically shared proportionally.

Step 5: Apply Parenting-Time Adjustments

This is where custody schedules directly affect support. When the non-residential parent exercises a significant percentage of parenting time — calculated based on hours the child is physically in their care, excluding school and structured daycare hours — the basic obligation is reduced:

• 35% to 39% parenting time — 10% reduction
• 40% to 44% — 20% reduction
• 45% to 49% — 30% reduction

If the non-residential parent hosts the child for more than 14 consecutive days — common during extended summer blocks — a temporary adjustment may reduce the monthly obligation by up to 50% for that period.

Equal Parenting Time Changes the Formula Entirely

When parents share equal physical residency (a true 50/50 split), the standard parenting-time adjustments don't apply. Instead, the guidelines require one of two formulas:

The Direct Expense Formula — one parent pays all the child's direct expenses (school fees, activities, gear), and the support worksheet balances incomes by halving the difference between the parents' proportionate percentages. The higher earner always pays support, even in a 50/50 split.

The Shared Expense Formula — both parents agree to split direct expenses proportionally and keep running receipts. This reduces the cash support transfer but requires cooperative financial communication and periodic true-ups.

Support Termination

Kansas child support doesn't automatically end on the child's 18th birthday if the child is still attending high school. Support continues until June 30 of the school year in which the child turns 18, or up to age 19 if the child is a bona fide student making progress toward graduation.

Using the Worksheet

The Kansas Child Support Worksheet is the official calculation tool and is filed with the court as part of the divorce proceedings. The worksheet walks through each step — but it doesn't explain the strategic choices, like how your schedule selection affects the parenting-time percentage or when the Direct Expense Formula produces a better result than the Shared Expense Formula.

Our Kansas Child Custody & Parenting Plan Guide includes a parenting-time calculator and walks you through each formula so you understand the financial implications of your schedule before you negotiate.

See more Kansas guides →