Washington Child Support Calculator (2025)

How Washington Calculates Child Support

Washington uses the Income Shares model for calculating child support, governed by RCW 26.19. This model is based on the economic principle that children should receive the same proportion of parental income they would have received if their parents lived together. The Income Shares approach is the most widely used child support model in the United States, and Washington's implementation includes several state-specific provisions.

Under Washington's system, the court determines each parent's income, combines those figures, and consults the guidelines schedule to find the basic child support obligation based on combined net income and number of children. Each parent's proportionate share is determined by their percentage of combined income. Additional costs for health insurance, childcare, and extraordinary expenses are added and divided proportionally.

The Washington guidelines create a rebuttable presumption that the calculated amount is the correct child support obligation. Courts can deviate only with specific written findings explaining why the guideline amount is unjust or inappropriate.

History and Legislative Background

Washington's child support guidelines are codified at RCW 26.19 (Revised Code of Washington, Chapter 26.19). The state adopted the Income Shares model in 1988 and has updated the guidelines periodically, with major revisions in 2009, 2019, and 2023. Washington's guidelines are notable for the concept of the residential schedule, which replaces the traditional custody terminology.

Washington is unique in using the residential schedule adjustment rather than a traditional overnight count. The state also has a distinctive self-support reserve of 125% of the federal poverty level, ensuring the non-custodial parent retains enough income for basic needs. Washington uses combined net income and has one of the most detailed economic tables in the country.

Understanding RCW 26.19

RCW 26.19 is the cornerstone of child support calculations in Washington. This comprehensive law establishes the framework that judges, attorneys, and parents must follow when determining child support obligations. RCW 26.19.020 defines income, RCW 26.19.035 provides the economic table (schedule), RCW 26.19.065 addresses deviations, and RCW 26.19.075 covers the residential schedule adjustment. The Washington State Child Support Schedule is published as a separate administrative document with extensive instructions.

The calculation follows a systematic approach: (1) determine each parent's gross income, (2) subtract permitted deductions, (3) combine adjusted incomes, (4) look up the basic obligation in the schedule, (5) calculate each parent's percentage share, (6) determine each parent's dollar share of the obligation, and (7) allocate additional expenses proportionally.

The Income Shares Model in Washington

Washington's adoption of the Income Shares model reflects a commitment to ensuring children benefit from both parents' financial resources. Economic research demonstrates that in intact families, both parents contribute to child-rearing costs in proportion to their incomes. The Income Shares model seeks to replicate this dynamic when parents live apart.

The model estimates what parents would collectively spend on their children if they shared a household. This estimate, the basic child support obligation, is derived from the Washington schedule based on economic data from the U.S. Department of Agriculture and other research on child-rearing expenditures. The obligation is then divided between parents based on their proportionate shares of combined income.

Unlike the Percentage of Income model used in some states (which considers only the non-custodial parent's income), the Income Shares model examines both parents' financial positions. This prevents inequitable results when one parent earns significantly more or less than the other, and ensures children of higher-income families receive support commensurate with the family's overall standard of living.

Washington Income Explained

Understanding what constitutes income under Washington child support law is essential for accurate calculations. Washington uses combined net income as the basis for determining the support obligation.

What Counts as Income in Washington

• Wages, salaries, and tips from all employment sources
• Commissions, bonuses, and overtime averaged over a reasonable period
• Self-employment income after legitimate business expenses
• Rental and royalty income from property and natural resources
• Interest, dividends, and investment income
• Pension, retirement, and annuity payments
• Social Security benefits of all types
• Workers' compensation and disability benefits
• Unemployment compensation
• Alimony received from other relationships
• Trust income and estate distributions
• Military pay and allowances
• Severance pay and strike benefits
• Capital gains from sale of assets

Allowable Deductions

• Federal, state, and local income taxes
• FICA taxes (Social Security and Medicare)
• Mandatory retirement contributions required by employer
• Pre-existing child support orders actually being paid
• Pre-existing alimony obligations under court order
• Mandatory union dues (where applicable)

Imputation of Income

Washington courts may impute income to a parent who is voluntarily unemployed or underemployed. The court considers the parent's age, education, work experience, health, available jobs in the community, and prior earnings history. Imputation prevents a parent from artificially reducing their support obligation by choosing not to work or accepting employment below their capacity. Courts will not impute income to parents with documented disabilities or those caring for very young children where childcare costs would exceed potential earnings.

The Washington Support Schedule

The Washington child support guidelines schedule lists base monthly support obligations for various levels of combined net income and different numbers of children. Below is a representative excerpt:

The schedule amounts represent the estimated total cost of raising children at each income level, derived from economic research. As income rises, the obligation increases but at a decreasing marginal rate. For incomes above the schedule maximum, courts typically extrapolate or exercise discretion based on the children's demonstrated needs.

How to Read the Schedule

Locate the row closest to the parents' combined net income. If the exact amount does not appear, interpolate between the two nearest values. Then look across to the column for the number of children. The result is the base child support obligation to be divided between parents proportionally.

Shared Custody Adjustments

Washington recognizes that shared physical custody arrangements require modified support calculations. Washington uses a residential schedule adjustment rather than a fixed overnight threshold. When the child spends significant time in both households (typically 35% or more with the non-residential parent), the court applies a whole-family formula. Each parent's obligation is computed and adjusted based on the residential schedule percentages. The obligations are then offset.

The Shared Custody Calculation

1. Calculate the base child support obligation using the standard schedule
2. Multiply the base obligation by 1.5 to account for duplicated household costs
3. Determine each parent's proportionate share based on income percentage
4. Multiply each parent's share by the percentage of time the child spends with the other parent
5. Offset the two amounts; the parent with the higher obligation pays the difference

This adjustment prevents the inequitable result that would occur if the standard formula were applied to shared custody, where both parents bear significant direct costs. The multiplier acknowledges increased total household costs when a child maintains two primary residences.

When Courts Deviate from Guidelines

While Washington's guidelines establish a presumptive correct amount, courts retain discretion to deviate when strict application would produce an unjust result. Any deviation requires specific written findings of fact.

Common grounds for deviation include:

• Extraordinary medical or dental expenses for a child with special healthcare needs
• Special educational expenses including private school or tutoring
• Travel costs for long-distance visitation
• Seasonal or variable income making standard calculations unreliable
• Combined income exceeding the schedule maximum
• Extraordinary tax consequences
• A child's independent income or resources
• Substantial debt from the marriage for family necessities
• In-kind contributions offsetting the support obligation

Courts exercise deviation authority sparingly. Data indicates deviations occur in fewer than 15% of cases, underscoring the strength of the guideline presumption.

How to Modify Child Support in Washington

Child support orders in Washington can be modified when there has been a substantial change of circumstances, defined as a change that would produce a support amount differing by at least $25 or 10% from the existing order.

Common grounds for modification include:

• Significant change in either parent's income
• Involuntary job loss or reduction in hours
• Change in custody or parenting time arrangement
• A child reaching majority or becoming emancipated
• Change in the child's medical or educational needs
• Significant change in health insurance or childcare costs

The Modification Process

File a motion to modify with the court that issued the original order. Provide current financial documentation. Both parents will exchange updated income information. Most uncontested modifications are completed within 60 to 120 days. Modifications are effective from the filing date, not retroactively, so parents experiencing changes should file promptly.

Enforcement of Washington Child Support

Washington's child support enforcement is handled through the Washington Division of Child Support (DCS) within the Department of Social and Health Services (DSHS).

Enforcement tools include:

• Income withholding/wage garnishment: Standard method for all orders
• Contempt of court: Fines and imprisonment for willful non-payment
• License suspension: Driver's, professional, and recreational licenses
• Tax refund interception: Both state and federal refunds
• Property liens: Real estate, vehicles, and financial accounts
• Credit bureau reporting: Mandatory reporting of past-due amounts
• Passport denial: For arrearages over $2,500
• Bank account seizure: Freezing and seizing funds

Washington participates in the Uniform Interstate Family Support Act (UIFSA) for interstate enforcement. Past-due support accrues 12% per annum on child support judgments. The state collects approximately $900 million in child support annually.

Duration of Child Support in Washington

In Washington, child support continues until the child reaches age 18, or through high school completion if the child is still in school at 18 (but not beyond age 19). Support may terminate earlier if the child marries, enlists in the military, or is legally emancipated. For children with significant disabilities preventing self-support, courts may order continued support beyond the standard age. Each case is evaluated individually based on the child's specific circumstances and needs.

Tax Implications

Under current federal tax law, child support payments are not tax-deductible for the paying parent and are not taxable income for the receiving parent. The dependency exemption for children of separated parents is generally claimed by the custodial parent unless released via IRS Form 8332. Washington courts sometimes address exemption allocation as part of the overall support determination.

Frequently Asked Questions

Other State Child Support Calculators

Child support laws vary significantly by state. If you need to calculate child support in another state, use one of our other free calculators: