Understanding the Oregon worksheet
OAR 137-050-0700 to -0765 · the rules behind FairShare's Oregon calculator and the state's official calculator.
The big picture
Oregon uses the income shares model: the guideline estimates what the parents would spend on the children if they lived together, then splits that amount in proportion to each parent's income. Both parents' finances matter - there is no single "payer's" formula.
Adjusted income (section 1)
Each parent starts from monthly income (actual, or what a parent could earn when a court presumes potential income), then adds spousal support received and subtracts spousal support paid, mandatory union dues, and the cost of the parent's own health insurance. A parent supporting other children (non-joint children) gets a deduction computed from the same scale. What remains is adjusted income, and each parent's share of the combined total sets their share of everything that follows.
The self-support reserve
Before any support is measured, each parent keeps $1,729 a month (OAR 137-050-0745, effective July 1, 2026) for their own basic needs - the amount tracks the federal poverty guideline and is re-set every July 1. Support obligations cannot reach into that reserve, which is why low incomes can produce small or minimum-level orders.
The basic support obligation (section 2)
The combined adjusted income and the number of joint children look up a monthly amount on Oregon's obligation scale. The scale has rows every $50 up to $30,000 of combined monthly income; between rows the lower row applies, and above $30,000 the top row applies (a court can be asked to go higher). More than ten children use the ten-child column.
Child care and health care (sections 3-5)
Work-related child care costs for children under 13 (or disabled) are shared by income share. Health care coverage for the children is ordered from whichever parent can provide it at a reasonable cost - capped at 4% of each parent's adjusted income, with $0 expected from a parent earning at or below full-time highest Oregon minimum wage. When neither parent has coverage available, cash medical support (that same reasonable-cost amount) can be ordered instead. Whoever actually pays a cost gets credited for it, so nothing is paid twice.
The parenting time credit (section 6)
Overnights matter from the very first one. The credit follows a smooth curve (OAR 137-050-0730) - no cliffs, no thresholds: at zero overnights the credit is 0%, at 182.5 overnights (equal time) it is 50%, and at 365 it is 100%. The worksheet uses each parent's average annual overnights over two years, and both parents' overnights must total 365. Blocks of 4 to 12 hours without an overnight can count as half days.
Who pays (sections 7-9)
After credits, the parent with the higher net obligation for the minor children pays the difference. A $100-a-month minimum order is presumed unless an exception applies (incarceration, disability benefits as sole income, and similar). Social Security or veterans benefits paid to the children because of a parent's disability or retirement reduce that parent's obligation dollar for dollar.
Children Attending School
Oregon support does not stop at 18: an unmarried child aged 18 to 20 who is enrolled in school at least half time is a Child Attending School (ORS 107.108), and their share of support is paid directly to the child. That is why the worksheet can obligate both parents at once, and why FairShare's Oregon results sometimes show two amounts.
The number is a starting point
The guideline amount is presumed correct, but a court can adjust it for seventeen listed rebuttal factors (OAR 137-050-0760) - other resources, special hardships, the needs of other dependents, and more - and parents can agree to any amount within ±15% of the guideline (OAR 137-050-0765). If a figure surprises you, the worksheet lines on the calculator show exactly where it came from.
FairShare provides estimates for informational purposes only - not legal advice. Actual support obligations are determined by the court under your state's guidelines. See the terms.