How Washington Calculates Child Support
Washington uses the Income Shares model to determine child support obligations. This page explains the guidelines, formula, and key factors.
Model Type
Income Shares
Income-shares schedule based on combined parental income and number of children; prorated by each parent’s share of income; adjusted by parenting time (as applicable) and add-ons (childcare/insurance/medical) per state rule.
Income Basis & Definitions
net monthly income (RCW 26.19.071)
Selects the base-support amount from the schedule/table.
Source: RCW 26.19.020 economic tableParenting Time Handling
Calculator selects custody model/worksheet (sole/shared/split/joint) and applies corresponding formula.
Source: Custody/worksheet applicability and parenting-time adjustmentResidential schedule/parenting time is handled via deviations; capture as deviation flag with details.
Source: Residential schedule deviation standardsDeductions & Adjustments
Adjustments/credits for other dependents or court-ordered support for other children (state-specific).
Source: Other children / preexisting support adjustmentIf the guideline adjusts for spousal support (paid/received), capture amount.
Source: Spousal support (alimony/maintenance) adjustmentAdd-Ons & Allocation
Work-related childcare costs added and allocated between parents.
Source: Childcare add-onChild’s health insurance premium share and uninsured/unreimbursed medical allocation.
Source: Medical support (insurance + uninsured medical)Caps, Minimums & Deviations
If guideline table caps at an income level, above-cap support is typically discretionary with findings.
Source: Maximum schedule income / above-cap handlingDeviation allowed for enumerated factors; requires findings (court-determined).
Source: Deviation factors / findings