Washington Child Support Calculator

At $6,000 per month in combined monthly net income, Washington's guidelines produce roughly $681/month for 1 child, $1,034/month for 2 children, $1,242/month for 3 children, $1,388/month for 4 children. These figures come from running Washington's own guideline formula, but they hold several things constant -- assumes the higher earner has 65% of the combined NET income shown, the children live primarily with the lower earner, neither parent has other biological or legal children, and no health care, day care, or special expenses. Washington has no parenting-time credit, so the residential schedule does not change these figures. Two rows look unusual and are correct: the $2,000 row is below the economic table's $2,200 floor, where only the $50-per-child presumptive minimum applies; and the $4,000 row is flat across every child count because the paying parent's income sits just $206 above the $2,394 self-support reserve, which caps their obligation at that $206 no matter how many children there are. Washington raised the reserve from 125% to 180% of the federal poverty guideline on January 1, 2026, so it now limits support in many ordinary cases. Your actual number depends on both parents' incomes, your parenting-time schedule, and add-on costs like childcare and health insurance, so run the calculator for your own case.

Washington uses the Income Shares model. Washington looks up a PER-CHILD amount from its economic table by combined monthly net income and number of children, multiplies it by the number of children, and splits the result by each parent's share of income. Unlike most states there is no parenting-time credit at all — the number of overnights does not change the guideline amount.

Washington's guideline runs on combined monthly net income. That distinction matters: entering gross income into a formula built on net income (or the reverse) produces a materially wrong figure. Most states count income from essentially any regular source -- wages, self-employment, bonuses, commissions, rental and investment income, and many benefits -- not just salary.

Not necessarily. In Washington: no credit and no threshold — a court may reduce the payment for a significant residential schedule, but only as a discretionary deviation with written findings. Because the guideline also weighs each parent's share of income, a significantly higher earner can still owe support at an even time split.

This calculator's core formula has been verified against the primary source, with any unimplemented rules listed openly rather than hidden. It implements the guideline in effect as of 2026-01-01, and a human last checked it against the primary source on 2026-09-20. Sources: RCW 26.19.020 — Child support economic table (as replaced by 2025 c 272 § 14); RCW 26.19.071 — Standards for determination of income; RCW 26.19.065 — Limitations and the self-support reserve; WSCSS Economic Table (01/2026), Administrative Office of the Courts. It is still an estimate, not a court order -- a judge can order a different amount, and this is not legal advice.

The Washington guideline this calculator implements took legal effect on 2026-01-01. States revise their guidelines periodically -- federal rules require each state to review its guidelines at least once every four years -- so a figure from an older calculator or article may reflect a superseded rule.

The 479-row economic table was parsed from the Legislature's HTML rendering of RCW 26.19.020 and cross-checked cell-for-cell against the AOC's own 01/2026 PDF (2,395 of 2,395 cells identical) and against DCS's 01/2019 pamphlet over the 99 overlapping rows (495 of 495 identical). This is the strongest schedule provenance of any state on this site. Washington's economic table gives a PER-CHILD amount that the worksheet multiplies by the number of children, unlike every other income-shares schedule here. Its age-bracket columns (0-11 / 12-18) were eliminated effective 2019-01-01; the Administrative Office of the Courts still serves two superseded PDFs showing them, which this calculator does not use. Net income is entered directly rather than estimated from gross. RCW 26.19.071(5) is a closed list of amounts actually paid — mandatory pension contributions, union dues, and L&I industrial insurance premiums cannot be derived from gross income (L&I is an hourly, employer-risk-class figure), and Washington publishes no gross-to-net conversion table. The result is only as accurate as the net figures entered. The self-support reserve ($2,394/month, 180% of the 2026 federal poverty guideline for one person) rose sharply on 2026-01-01 and must be refreshed each January when HHS republishes the guidelines. It is tracked in docs/guideline-watch/watchlist.json. The income-share proportion is rounded to three decimal places, which is what every one of the AOC's published worked examples does and is required to reproduce their figures exactly. The instruction text itself only says 'divide,' so this is inferred from the examples rather than stated as a rule. The AOC's own line-15 worked example is internally inconsistent: it adds the parent's line 7 rather than the limited line 9, silently dropping the self-support-reserve limitation it demonstrated one line earlier. This calculator implements the worksheet's stated formula (line 9 + line 14), not the example's arithmetic. No parenting-time credit is computed, because Washington has none — no overnight threshold, no percentage-of-time formula, and no shared-parenting worksheet. A residential-schedule deviation under RCW 26.19.075(1)(d) is available but is discretionary, evidence-based, and requires written findings, so it is disclosed rather than estimated. The 45% net-income limitation (RCW 26.19.065(1)) is surfaced as an informational figure, not applied as a cap. The official worksheet places it in 'Part VII: Additional Informational Calculations' and the standard calculation never references it; it also measures a parent's obligation across all of their children in every case, which a single-case calculator cannot know. Several third-party Washington calculators apply it as a hard cap — that is not what the worksheet does. For an even (50/50) residential schedule, Washington fixes no rule for which parent makes the transfer payment; the worksheet computes both columns and leaves the direction to the parenting plan and the court. This calculator shows the larger figure and says the direction is undetermined. The residential split adjustment (each parent the primary residential parent for a different child, per the AOC's optional RSA attachment) is not implemented, consistent with every other income-shares state here. Postsecondary educational support (RCW 26.19.090, advisory and not mandatory), the three-parent worksheet, imputed income (RCW 26.19.071(6)), and the RCW 26.19.075 deviation factors are disclosed rather than computed. If any of these apply to your case, treat the estimate as a starting point and confirm the figure with an attorney, a mediator, or Washington's official worksheet.

Yes. The figure produced by Washington's Income Shares guideline is presumptive, not mandatory: a court can order a different amount when applying the guideline would be unjust or inappropriate for the specific case, and generally must state its reason on the record. Common grounds include extraordinary medical or educational expenses, a child's special needs, or costs the formula does not capture. Washington's guideline is set out in RCW 26.19.020 — Child support economic table (as replaced by 2025 c 272 § 14).

You have to file for a modification -- a change in your circumstances does not change what you owe on its own. Washington, like most states, requires a substantial change in circumstances: a significant involuntary income change, a change in the parenting schedule, or a material change in the child's needs. Until a court or the state child support agency issues a new order, the existing amount stays fully enforceable and arrears keep accruing, and a modification is generally not applied retroactively before the date you filed -- so filing promptly matters. In Washington, modifications are handled through DSHS Division of Child Support.

Washington publishes it directly: "Washington State Child Support Schedule (WSCSS) Worksheet Calculator — DSHS". This site's calculator is a fast estimate built on the same published guideline, not a replacement for the official form -- a court filing generally requires the state's own worksheet. The link is in the Washington Resources section on this page.