How to calculate Alimony Child Support in Washington

Quick takeaways

• Washington uses two related but separate frameworks:

  • Child support uses the Washington State child support schedule under RCW 26.19.020, calculated using the worksheet/standards approach under RCW 26.19.071.
  • Maintenance (often called “alimony”) is addressed separately under RCW 26.09.090.
• DocketMath’s “alimony-child-support” calculator helps you organize the required Washington inputs and follow jurisdiction-aware logic so you can review results in a worksheet-style format.
• Deviation is possible but limited: Washington allows deviations from the standard calculation under RCW 26.19.075 only when the statutory conditions are met. If the facts don’t match a deviation pathway, your result may stay on the standard calculation.
• Default-period clarification: No claim-type-specific sub-rule was found in the provided materials, so this guide uses the general/default period described by the cited statutory framework (schedule → worksheet standards → deviation review), without adding a special “claim-type” branch.

Inputs you need

Before you open DocketMath, gather the inputs that drive Washington’s worksheet mechanics. The goal is consistency: the same numbers should flow into both the child support and maintenance parts of your analysis.

A. Child support inputs (Washington State schedule)

Washington child support is built from RCW 26.19.020 (schedule) and implemented through the worksheet/standards under RCW 26.19.071.

Start with:

• Parents’ combined monthly net income

  • You’ll typically compute each parent’s net monthly income, then sum them for the combined figure used to select the schedule line under RCW 26.19.020.
• Number of children covered by the calculation
• Ages of the children

  • The schedule selection depends on number + ages (not just number).
• Worksheet-required adjustments (if your tool requests them)

  • DocketMath may ask for factors tied to the residential/parenting-time pattern. If it prompts you for those values, use them consistently with your Washington parenting-time facts.

Also be prepared for:

• Income adjustments / categorization questions

  • Washington’s worksheet approach under RCW 26.19.071 can require you to treat certain components in specific ways. DocketMath should prompt you where that matters.

B. Maintenance (“alimony”) inputs (separate statutory framework)

Maintenance is not derived from the child support schedule table in the same way. It is governed by RCW 26.09.090, and you’ll generally need:

• Each party’s income and financial circumstances

  • Earned income and other sources; what each party can realistically pay toward maintenance/needs.
• Needs and ability-to-pay details

  • The analysis centers on the statutory financial factors, rather than the schedule-table method.
• Any duration-related context (if applicable to your scenario)

  • DocketMath can help you model effects of duration parameters if it includes them in the worksheet.

C. Deviation inputs (may change child support)

Washington allows deviations under RCW 26.19.075 in defined circumstances.

Collect what you plan to rely on for a deviation basis, such as:

• Evidence of unusual costs or specific circumstances that affect fairness under the standard calculation.
• Information that aligns with the statutory deviation pathway you intend to use.

Practical tip: If you don’t have deviation facts that fit the statutory pathway, it’s usually safer to rely on the standard schedule/worksheet output rather than forcing a deviation entry.

How the calculation works

DocketMath applies Washington’s jurisdiction-aware rules in a structured sequence. Think of it as:

1. Child support baseline (schedule selection)
2. Worksheet standards (RCW 26.19.071 methodology)
3. Deviation review (if you enter a deviation pathway)
4. Maintenance calculated separately under RCW 26.09.090

1) Child support baseline: schedule based on combined net income + ages

Under RCW 26.19.020, the basic child support obligation comes from the economic table selected using:

• Parents’ combined monthly net income, and
• Number and ages of the children

So the first “lever” is the combined net income figure, and the second “lever” is the age structure that determines which table line applies.

2) Worksheet standards: apply RCW 26.19.071 methodology

RCW 26.19.071 governs how the schedule amount is carried into a worksheet calculation.

In practical terms, the worksheet stage determines how your inputs are treated and applied, such as:

• how net income is derived and categorized,
• how the calculation reflects the parties’ circumstances using Washington’s standards, and
• how any worksheet-required adjustments are reflected before deviations are considered.

DocketMath is meant to keep this pipeline visible: inputs → worksheet logic → output, so you can see what changed when you change a number.

3) Deviation check: RCW 26.19.075

Once the worksheet output is formed, RCW 26.19.075 addresses when a court may deviate from the standard calculation.

In a DocketMath workflow, this often works like:

• No deviation basis entered → you follow the schedule-based worksheet output.
• Deviation basis entered → the calculator may show an adjusted result consistent with the deviation workflow.

4) Maintenance (“alimony”) calculated separately under RCW 26.09.090

Washington maintenance is governed by RCW 26.09.090 and does not use the child support schedule table.

Why that matters:

• A change in child-related income might affect child support through combined net income under RCW 26.19.020, but it may affect maintenance differently because maintenance focuses on broader financial circumstances and statutory factors.
• Even if the “income number” is the same, the legal framework and worksheet mechanics are different, so the outputs can move independently.

5) Default-period clarification (no claim-type-specific branch)

Based on the provided note, this guide uses the general/default method derived from the cited statutes:

• schedule framework (RCW 26.19.020),
• worksheet standards (RCW 26.19.071),
• deviations (RCW 26.19.075).

No claim-type-specific sub-rule is introduced beyond what these statutes prescribe at a general level.

Common pitfalls

Small input mismatches can create big swings in outputs. Watch for these common issues when using DocketMath and applying Washington’s structure.

1) Mixing child support schedule logic with maintenance logic

Because RCW 26.19.020 (schedule/worksheet) drives child support, while RCW 26.09.090 governs maintenance, you can’t treat one category’s math as the explanation for the other.

• Net income shifts often move child support through the schedule.
• Financial circumstances and statutory factors drive maintenance, which may not track schedule changes one-to-one.

2) Entering the wrong child ages (or omitting a child)

Washington’s schedule selection depends on ages and number of children under RCW 26.19.020. If ages are wrong (or a child is missed), the table line can change.

3) Entering deviation facts without using a deviation pathway

Under RCW 26.19.075, deviation requires statutory grounding.

• If the calculator session doesn’t capture a deviation pathway (or you don’t enter the deviation inputs the tool expects), the result may default to the standard worksheet output.

4) Using gross income where the schedule needs net income

The schedule framework is keyed to monthly net income under RCW 26.19.020.

If you enter gross pay instead of net, combined income can be overstated and can push the worksheet into the wrong range.

5) Overlooking what the worksheet standards require

RCW 26.19.071 matters because the worksheet method governs how income is treated and applied.

Two people can use the same combined net income number but still reach different outputs if the worksheet categorization or adjustments differ.

Sources and references

• RCW 26.19.020 — Washington State child support schedule
  https://app.leg.wa.gov/RCW/default.aspx?cite=26.19.020
• RCW 26.19.071 — Worksheet/standards for child support
• RCW 26.19.075 — Deviations from the standard calculation
• RCW 26.09.090 — Maintenance (alimony)

Next steps

1. Open DocketMath’s Washington jurisdiction calculator here: /tools/alimony-child-support
2. Run at least two scenarios:

   • Baseline run (standard calculation) using the schedule/worksheet approach under RCW 26.19.020 and RCW 26.19.071.
   • Deviation run (only if you have deviation facts) aligned with RCW 26.19.075.
3. Compare outputs and note sensitivity:

   • Change combined monthly net income by a small amount (e.g., ±$250/month) to see how child support responds.
   • Update one child’s age band only when it reflects reality and rerun to see how schedule selection changes.

Related reading

• How Alimony Child Support rules vary in New York — What varies by jurisdiction
• [How to calculate