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Free Washington State child support calculator for combined monthly gross income, an illustrative basic obligation from a guideline-style schedule (with interpolation), and pro-rata allocation to estimate the non-custodial payer’s share. Browse legal and compliance calculators for more family-law tools.
Last updated: April 19, 2026
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Washington worksheets use gross income with statutory deductions and adjustments (simplified here).
Monthly payment estimate
$998.72
Total basic obligation
$1,664.54
Combined gross / mo
$10,000.00
NCP pro-rata
60.00%
CP pro-rata
40.00%
Schedule cap (node)
$35,000.00+
Educational estimate only
Not a substitute for the Washington State Child Support Schedule, worksheets, or Division of Child Support tools. Use official forms for court and administrative cases.
RCW 26.19 style
1–6 children columns
Interpolates between income nodes consistent with table-style extrapolation.
Pro-rata model
NCP pays × (NCP ÷ combined)
Applies each parent’s percentage of combined gross income to the base obligation.
Calibration
Verify with WA worksheets
Dollar amounts are illustrative; use published schedules for hearings and orders.
Output
Monthly dollars to pay
Shows the payer’s share of the base obligation before transfers and adjustments.
Children count
1 – 6 children
Matches the obligation column for the number of children in the order.
Use case
Intake & screening
Helps you compare scenarios before filing or using court and DCS tools.
For $4,000 custodial and $6,000 non-custodial gross monthly income with two children ($10,000 combined):
Estimated NCP monthly payment
$998.72
Basic obligation (2 children)
$1,664.54
Our Washington State child support calculator applies the income-shares framework used with Washington’s guidelines: combine parents’ gross incomes (simplified here), determine a basic monthly child support obligation from an illustrative schedule with interpolation between income points, then allocate that obligation using each parent’s percentage of combined income. The non-custodial parent’s estimated payment is their pro-rata share of the basic obligation. See other family-law calculators for comparison.
Basic obligation = Schedule lookup(combined gross income, # children)NCP payment = Basic obligation × (NCP income ÷ combined income)Combined income is compared to schedule points up to $35,000.00 per month in this tool; higher incomes extrapolate from the top segment.
Washington income shares + base obligation (conceptual)
Illustrative result: basic two-child obligation ≈ $1,664.54; NCP payment ≈ $998.72 (before transfers and add-ons).
Same $10,000 combined gross: select one child in the calculator for a lower base obligation and proportional payment.
Use Washington’s published schedule and worksheets for court orders and DCS cases.
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