Plain-language definitions of key terms used in Washington State child support calculations and court filings.
Washington State uses the Income Shares Model under RCW 26.19 to calculate child support. Both parents net incomes are combined to determine the basic support obligation from the 2026 economic table. Each parent then pays their proportional share based on their percentage of combined income.
Understanding the key legal terms in this process is essential for parents completing the WSCSS worksheet, attending court hearings, or reviewing an existing support order. This glossary covers all 20 core terms used in the official 2026 Washington State Child Support Schedule including income definitions, calculation methods, court adjustment factors, limitation standards, and enforcement terminology.
All definitions are based on RCW 26.19 and the 2026 AOC economic table effective January 1 2026.
The Self-Support Reserve (SSR) is a minimum income protection limit set by Washington State to ensure a paying parent is not left impoverished after paying child support. In 2026, the SSR is $2,394 (180% of the federal poverty level).
Read SSR GuideA deviation is a court-approved adjustment to the standard presumptive child support amount. It allows a judge to increase or decrease the payment based on specific 'good cause' factors not captured in the basic economic tables.
Read Deviation GuideImputed income is an estimated income amount assigned by a court to a parent who is voluntarily unemployed, underemployed, or fails to provide sufficient financial documentation.
Read Imputed Income GuideThe transfer payment is the final, legally enforceable dollar amount that one parent must pay to the other parent each month for child support.
Read Transfer Payment GuideCombined net income is the total sum of both Parent 1 and Parent 2's monthly income after all mandatory state deductions (like taxes, union dues, and L&I) are removed.
Read Net Income GuideExtraordinary expenses are large, out-of-pocket costs that are NOT covered by the basic child support transfer payment. By Washington law, these must be shared proportionately based on each parent's income percentage.
Read Extraordinary Expenses GuideThe basic child support obligation is the monthly amount determined from the 2026 Washington economic table based on both parents combined net income and number of children. It is the starting point for calculating the final transfer payment before any adjustments or credits are applied.
Read Basic Obligation Guide →Washington uses the Income Shares Model to calculate child support. Both parents net incomes are combined and used to look up the basic obligation in the economic table. Each parent then pays their proportional share based on their percentage of combined income.
Read Income Shares Guide →A proportional share is each parent's percentage of the combined net income. This percentage determines each parent's share of the basic obligation and all extraordinary expenses including healthcare and daycare.
Read Proportional Share Guide →Gross monthly income includes all income from any source before deductions — wages, salaries, business income, rental income, investment income, pension, Social Security, and unemployment benefits. Washington law requires full disclosure of all income sources under RCW 26.19.071.
Read Gross Income Guide →Net monthly income is gross income after subtracting mandatory deductions including federal and state income taxes, FICA, mandatory union dues, required pension contributions, and state insurance premiums. The 2026 economic table uses net income not gross income.
Read Net Income Guide →The standard calculation is the presumptive monthly child support amount determined by following the Washington child support schedule exactly. Courts must use this amount unless specific written reasons for deviation are provided under RCW 26.19.035.
Read Standard Calculation Guide →A parenting time credit is a deviation that reduces child support when the paying parent has significant residential time with the child. Under RCW 26.19.075(1)(d), the court has discretion to deviate based on actual increased expenses for the paying parent and decreased expenses for the receiving parent.
Read Parenting Time Credit Guide →The economic table is the official Washington State chart used to determine the basic child support obligation per child. It lists combined monthly net incomes from $2,200 to $50,000 against family size from 1 to 5 children. Updated January 1 2026 under RCW 26.19.020.
Read Economic Table Guide →The residential schedule defines when each parent has the child. It determines which parent is the primary residential parent for child support purposes and may be used to request a parenting time deviation under RCW 26.09.187.
Read Residential Schedule Guide →Monthly healthcare costs for children including insurance premiums, copays, dental, vision, and mental health treatment are not included in the basic child support obligation. They must be shared proportionally based on each parent's income share under RCW 26.19.080.
Read Healthcare Expenses Guide →Work-related daycare and childcare costs are not included in the basic child support obligation. They are treated as extraordinary expenses and shared proportionally between parents based on their income share percentages under RCW 26.19.080.
Read Daycare Expenses Guide →A parent is considered voluntarily unemployed if they choose not to work or work below their earning capacity without good cause. Washington courts will impute income to voluntarily unemployed parents based on their work history and local job market under RCW 26.19.071.
Read Voluntary Unemployment Guide →A support modification is a court-approved change to an existing child support order. In Washington a modification requires showing a substantial change in circumstances — typically a 15% or more change in either parent's net income under RCW 26.09.170.
Read Support Modification Guide →Washington law limits child support to 45% of a parent's net monthly income for all their biological or legal children combined. Courts may exceed this cap only for good cause including substantial wealth or special needs of the children under RCW 26.19.065.
Read Income Cap GuideNow that you understand the key terms use our free 2026 Washington child support calculator or complete the full 8-part official worksheet.
Our editorial methodology ensures all definitions and calculations comply with the 2026 Washington State economic tables.
Our Methodology