Calculate Child Support
Before taxes. Include wages, self-employment, bonuses.
Washington uses the Income Shares — both incomes required.
0 = no custody · 91 = 25% · 182 = 50/50 · 365 = full custody
$0
estimated monthly support payment
⚠️ Estimate only. Actual court-ordered amounts may vary. Verify with a licensed Washington family law attorney.
ℹ️ Washington uses the Income Shares — Washington uses Income Shares. The Economic Table covers combined monthly income from $2,200 to $50,000 (2026). Self-support reserve: $2,394/month.
How Child Support Works in Washington
Washington uses the Income Shares to determine child support obligations.
The Income Shares model combines both parents' incomes, finds the basic support obligation from a state schedule, then divides it proportionally. More parenting time (overnights) reduces the non-custodial parent's payment through a parenting time credit.
How Washington Compares to Other States
See how Washington's child support rules compare to other states.
| State | Formula | Support Ends | Arrears Rate | Mod. Threshold |
|---|---|---|---|---|
| ★ Washington (you) | Income Shares | 18 | 12% | 25% |
| Delaware | Melson Formula | 18 | 5% | 10% |
| Idaho | Percentage of Income | 18 | 5% | 15% |
| Michigan | Income Shares | 18 | 5% | 10% |
| Ohio | Income Shares | 18 | 5% | 10% |
| Alaska | Percentage of Income | 18 | 6% | 15% |
| Florida | Income Shares | 18 | 6% | 15% |
| Louisiana | Income Shares | 18 | 6% | 25% |
| New Hampshire | Income Shares | 18 | 6% | 15% |
Showing 8 comparison states. View all 50 states →
Frequently Asked Questions
How is child support calculated in Washington?
Washington uses the Income Shares model. Washington uses Income Shares. The Economic Table covers combined monthly income from $2,200 to $50,000 (2026). Self-support reserve: $2,394/month.
When does child support end in Washington?
Child support generally ends when the child turns 18 in Washington.
Can I modify child support in Washington?
Yes. Washington requires a 25% or greater change in income to qualify. Use our modification checker →
Does 50/50 custody eliminate child support in Washington?
Not automatically. The higher-earning parent typically still pays support with 50/50 custody. See our 50/50 guide →
What income is used for child support in Washington?
Income includes wages, self-employment, bonuses, rental income, unemployment benefits, disability payments, and Social Security. Courts may impute income if a parent is voluntarily underemployed.