Quick answer: Oregon uses an income-shares formula in OAR 137-050-0700 to 0765. Each parent’s income is adjusted by deducting union dues, the parent’s own health insurance and spousal support owed, adding spousal support received and subtracting a non-joint child deduction. The combined adjusted income (up to $30,000 a month) is matched to the obligation scale for one to ten children, and each parent’s share follows his or her percentage of the combined income, but cannot exceed the income left after a self-support reserve of $1,729 (effective July 1, 2026). Child care for children under 13 (capped by age and region) and the children’s health coverage are shared by income, and each parent is credited for what he or she pays. A parenting time credit computed from a formula on the overnights (about 15% at 100 overnights, 50% at about 182) reduces each parent’s obligation; only the parent with the greater net obligation pays, and a $100 minimum order is presumed. The guideline amount is presumed just and appropriate and can be rebutted.
How the Oregon formula works
- Adjusted income, the scale and shares. See how the Oregon formula works.
- The parenting time credit. See the parenting time credit formula.
- Child care, health coverage and the reserve. See child care, health coverage and the self-support reserve.
What this calculator checks
The calculator follows the guideline rules with commentary effective July 1, 2026, with the obligation scale (581 rows read from the official appendix) and the parenting time credit formula (checked against the official table), and was checked against an independent re-implementation. It does not apply the 4% reasonable-cost test for health coverage, children attending school, split custody, Social Security or veterans benefit offsets or rebuttals.
Child support across Oregon
The guidelines apply in every Oregon circuit court and in Child Support Program cases, from Portland, Salem, Eugene, Gresham, Hillsboro or Bend. The formula amount is rebuttable on the criteria in OAR 137-050-0760.
Frequently asked questions
How is child support calculated in Oregon?
Each parent's adjusted income is combined, the obligation scale gives the basic obligation, each parent pays an income share limited by a $1,729 self-support reserve, and credits for parenting time, child care and health coverage decide who pays and how much.
How does Oregon’s parenting time credit work?
Each parent's credit percentage is computed from his or her overnights with a formula, about 15% at 100 overnights and 50% near 182, and multiplied by the basic obligation.
What is the Oregon minimum child support?
$100 a month is presumed, unless an exception such as disability benefits as the sole income applies.
What is the Oregon self-support reserve?
$1,729 a month for 2026: a parent's total obligation may not exceed income above it, except for the minimum order.
What is the highest income in the Oregon scale?
$30,000 of combined adjusted monthly income; above it the scale amount for $30,000 is used.