How Child Support Is Calculated in Washington State
Washington child support is calculated under the Washington State Child Support Schedule using both parents’ incomes. The calculation begins with a standard support amount, but the final amount may also be affected by health care and child care expenses, the residential schedule, other children a parent supports, and other circumstances recognized by Washington law.
The parent who pays support is not determined simply by labeling one parent “custodial” or “noncustodial.” Washington law refers to the final amount one parent is ordered to pay the other as the support transfer payment.
2026 Update: Washington made significant changes to the Child Support Schedule effective January 1, 2026. This article explains how child support is calculated under the current schedule. For a detailed explanation of what changed and how the changes may affect new and existing support orders, see our Washington Child Support Law Changes 2026 article.
What Goes Into a Washington Child Support Calculation?
Although every case is different, the calculation generally follows several steps:
- Determine each parent’s gross monthly income.
- Subtract allowable deductions to determine each parent’s net monthly income.
- Combine the parents’ net incomes.
- Use the Washington State Economic Table to determine the basic child support obligation.
- Allocate that obligation between the parents according to their respective shares of the combined net income.
- Add each parent’s share of health care, day care, and other applicable child-related expenses.
- Determine whether a deviation from the standard calculation is appropriate.
How Is Income Determined for Child Support?
Washington child support starts with each parent’s monthly income. Gross income can include wages, salary, commissions, bonuses, deferred compensation, overtime, investment income, retirement income, and income from self-employment or a business, subject to the exclusions and rules contained in the Child Support Schedule.
Allowable deductions are then subtracted to determine monthly net income. The court generally requires current pay stubs and the prior two years of tax returns to verify income and deductions.
Only the income of the parents whose child support obligation is being calculated is included in the basic support calculation. The income of a new spouse, domestic partner, or other adult in the household is not added to a parent’s income for purposes of calculating the basic support obligation, although household income and resources may become relevant to certain requests for a deviation.
How Is the Basic Child Support Obligation Calculated?
The basic child support obligation is determined from the Washington State Economic Table based on:
- The parents’ combined monthly net income; and
- The number of children for whom support is being calculated.
The current Economic Table does not vary the basic support amount based on the child’s age.
Once the table amount is determined, it is allocated between the parents according to each parent’s percentage of the combined monthly net income.
Example
Assume Parent A and Parent B each have monthly net income of $5,000. Their combined monthly net income is $10,000, and each parent earns 50% of the combined income.
For a family with two children and combined monthly net income of $10,000, the current Economic Table provides a basic support obligation of $1,099 per child, or $2,198 for two children.
Because each parent earns 50% of the combined income, each parent’s proportional share of the $2,198 basic obligation is $1,099. If Parent A is the parent ordered to make the support transfer payment, and there are no additional expenses, credits, limitations, or deviations, the simplified basic support amount would be $1,099 per month.
The actual support order may be different because the worksheets also account for additional expenses, credits, statutory limitations, and any deviation ordered by the court.
What Other Child Support Expenses Are Shared?
The Economic Table does not include all expenses associated with raising a child.
Under
RCW 26.19.080,
health care costs are generally shared between the parents in the same proportion as the basic child support obligation. These costs can include medical, dental, orthodontic, vision, mental health treatment, prescription medications, and similar health care expenses.
Day care and special child-rearing expenses are also outside the Economic Table and are generally divided according to the same proportional shares. The statute identifies tuition and long-distance transportation associated with residential time as examples of special child-rearing expenses.
The court has discretion to determine whether expenses ordered in addition to basic child support are necessary and reasonable. Other expenses, including extracurricular activities, may also be addressed by agreement or court order depending on the circumstances.
What Is a Child Support Deviation?
The amount produced under the Child Support Schedule before considering special circumstances is called the standard calculation. A deviation is an order for a different amount based on circumstances recognized by Washington law.
Some common reasons for requesting a deviation under
RCW 26.19.075
include the following:
Significant Residential Time
A court may deviate when a child spends a significant amount of time with the parent who would otherwise make the support transfer payment. In determining whether and how much to deviate, the court considers the increased expenses incurred by that parent and any decreased expenses in the other household.
A residential deviation cannot be granted if it would leave the household receiving support without sufficient resources to meet the child’s basic needs or if the child is receiving Temporary Assistance for Needy Families (TANF).
Nonrecurring Income
A court may deviate when a particular source of income included in the calculation is genuinely nonrecurring. Depending on the circumstances, that may include overtime, bonuses, contract-related benefits, or income from a second job. Washington law requires review of the nonrecurring income received during the previous two calendar years when considering this type of deviation.
Children From Other Relationships
A parent who owes a duty of support to children from another relationship may request a deviation. Those children are not simply added to the number of children used in the Economic Table. Instead, the court considers the support obligations and the circumstances of both households.
Does 50/50 Parenting Mean No Child Support?
No. A 50/50 residential schedule does not automatically eliminate child support in Washington.
The court first determines the standard calculation under the Child Support Schedule. A parent may then request a deviation based on significant residential time. Whether a deviation is granted, and the amount of any deviation, depends on the facts of the case and the statutory requirements.
As a result, one parent may still pay a support transfer payment even when the children spend approximately equal time with each parent, particularly when there is a significant difference in the parents’ incomes.
Why the Final Child Support Amount May Differ From the Table
The Economic Table is only one part of the calculation. The final support transfer payment may differ from a parent’s proportional share of the basic obligation because of health care costs, day care, special child-rearing expenses, statutory limitations, credits, or a deviation ordered by the court.
For that reason, simply looking up an amount on the Economic Table is not enough to determine the child support that will ultimately be ordered in a particular case.
At Weintraub Law Office, we have extensive experience in Washington child support law and support-related litigation. Founding attorney Boaz Weintraub is co-author of the
2022 Washington State Family Law Deskbook
chapter on child support.
Contact us for help with your Washington child support case.
Last updated: August 2026