Calculation is client-side, income figures are never transmitted or stored.
How Oregon Child Support Is Calculated
- Determine each parent's monthly gross adjusted income, then combine both for combined monthly gross adjusted income.
- Look up the basic child support obligation from the official Guidelines Scale for that combined income and number of children (up to 10).
- Each parent's share equals their income divided by combined income, applied to the basic obligation.
- Apply the parenting time credit: an exact logistic formula based on the paying parent's annual overnights (not a simple percentage table) reduces that parent's share.
- The result may not exceed the paying parent's income available for support (income minus the $1,522/month Self-Support Reserve), and a rebuttable $100/month minimum order applies.
- Above $30,000/month combined income, the obligation is the same as for $30,000/month rather than extrapolated further.
Oregon Child Support Worksheet Walkthrough
Example: combined gross adjusted income $5,000/month, 2 children, Parent A earns $3,000/mo (60% share), Parent B earns $2,000/mo (40% share) and is the noncustodial parent with 100 overnights/year.
- Basic child support obligation for $5,000 combined, 2 children (official scale): $1,136/month.
- Parent B's pre-credit share: 40% × $1,136 ≈ $454/month.
- Parenting time credit at 100/365 overnights: the logistic formula gives 15.4% of the basic obligation (≈$175), reducing Parent B's share to $280/month.
How This Calculator Works — Formula & Constants
Source: Oregon Department of Justice, Child Support Program (OAR 137-050) · Calcul déterministe — no AI, no arbitrary estimate.
Constants used
| Constant | Value | Source |
|---|
Formula
base_obligation = schedule_lookup(combined_income, children)
share_B = parentB_income / combined_income
total_obligation = base_obligation + childcare_cost + health_insurance_cost
obligation_B = total_obligation × share_B
obligation_B = obligation_B × (1 - custody_credit(overnights))
Deterministic calculation based on Oregon's official guideline schedule table. Verify against Oregon's official calculator for a court-ready figure.
FAQ
How is child support calculated in Oregon?
Determine each parent's monthly gross adjusted income, then combine both for combined monthly gross adjusted income. Look up the basic child support obligation from the official Guidelines Scale for that combined income and number of children (up to 10). Each parent's share equals their income divided by combined income, applied to the basic obligation. Apply the parenting time credit: an exact logistic formula based on the paying parent's annual overnights (not a simple percentage table) reduces that parent's share. The result may not exceed the paying parent's income available for support (income minus the $1,522/month Self-Support Reserve), and a rebuttable $100/month minimum order applies. Above $30,000/month combined income, the obligation is the same as for $30,000/month rather than extrapolated further.
How does Oregon's parenting time credit formula work?
Unlike most states, which use a lookup table for parenting-time credits, Oregon uses an exact mathematical formula: credit% = 1/(1+e^(-7.14×((overnights/365)-0.5))) - 0.0274 + (2×0.0274×(overnights/365)). This is a logistic (S-shaped) curve that produces a smooth, continuously increasing credit as overnights rise, reaching 50% at exactly equal (182.5/182.5) parenting time.
What is Oregon's Self-Support Reserve?
The Self-Support Reserve is $1,522/month as of the 2026 guidelines (based on the federal poverty guideline, multiplied by 1.167 for estimated taxes). The paying parent's total obligation may not exceed their income minus this reserve amount -- protecting low-income parents from being reduced below a basic subsistence level.
What happens if combined income is above $30,000/month in Oregon?
Above $30,000/month in combined gross adjusted income (or beyond 10 children), Oregon's guideline caps the obligation at the $30,000 schedule figure rather than extrapolating further. A newer scale with a $50,000 cap and 6 children columns has been proposed by Oregon's Guidelines Advisory Committee as of 2026 but is not yet adopted into the administrative rule.
Methodology & Source
Formula model: income shares. Effective 2007-02-09, guideline version 2007-OR-v1, last reviewed 2026-07-13.
Official source: Oregon Department of Justice, Child Support Program (OAR 137-050) (OAR 137-050-0700 to 137-050-0765).
Above $30,000/month combined gross income, or beyond 10 children, Oregon's schedule has no further value -- the obligation is the same as for $30,000/month (OAR 137-050-0725(3)-(4)), not extrapolated further. This calculator does not model split custody (each parent primary for at least one child) or the Social Security/veterans benefits dollar-for-dollar reduction.
Guideline figures transcribed from the primary source above and cross-checked against Oregon's official calculator/worksheet for multiple test scenarios — see our verification methodology.