How Oregon Calculates Child Support

Oregon uses the Income Shares model to determine child support obligations. This page explains the guidelines, formula, and key factors.

Model Type

Income Shares (OAR 137-050-0700 to 137-050-0765)

Oregon looks up a basic support obligation from a scale of combined monthly gross adjusted income and number of children, then applies a continuous parenting-time credit formula to each parent's own overnights rather than a sole/shared custody threshold.

Sources & Verification

Core formula verified; some gaps disclosed below

Guideline effective 2026-07-01 · last checked against the primary source 2026-09-07

Primary sources

OAR 137-050-0700 to 137-050-0765 — Child Support Guideline Rules Child Support Guideline Rules with Commentary (PDF, current through July 1, 2026)Updated Obligation Scale B — Table 1 (PDF)

What this calculator doesn't yet handle

The obligation scale (shared/or-schedule.ts) was extracted programmatically from the appendix PDF's glyph coordinates rather than transcribed from a machine-readable source, because the appendix's multi-line column headers garble both naive text extraction and pdftotext -layout. Validated for internal consistency (contiguous $50 bands, non-decreasing across both axes) and cross-checked against a second, independently-flawed extraction that happened to preserve correct order for its final page — see shared/or-schedule.ts's header for the full method. Not yet checked cell-by-cell against the source PDF.
Income is entered as actual gross income only — OAR 137-050-0715's potential/imputed income for a voluntarily unemployed or underemployed parent is not modeled.
Adjusted income (OAR 137-050-0720) implements only spousal support paid/received and the non-joint child deduction. Union dues and the parent's own health-insurance-premium deduction are not collected.
The non-joint child deduction ((2)(e)) uses a single-parent scale lookup on that parent's own post-spousal-support income, per the rule's own abbreviated method — the rule itself calls this 'only a rough estimate.'
Child care costs are not capped against OAR 137-050-0735(3)'s metro-area maximum table, and the disabled-child / under-13 eligibility condition in (1) is not enforced — any entered amount is used as-is.
Medical support (OAR 137-050-0750) is simplified to a single children's health-insurance-premium add-on, prorated by income share. The 4%-of-income reasonable-cost cap, the minimum-wage carve-outs, coverage-selection rules, and cash medical support (when neither parent has coverage) are not implemented.
Split custody (OAR 137-050-0730(3), each parent primary for a different child) is not implemented — the calculator collects one overnight split applied to all children.
The Social Security/Veterans benefits dollar-for-dollar reduction (OAR 137-050-0740) and the minimum order's incarceration/public-benefits/disability-income exceptions ((0755(2)(d)) are not calculated, only the equal-overnights exception is checked.
The 'Children Attending School' (18-year-olds still in high school) distinction from ordinary minor children is not modeled — all children in a calculation are treated as minor children.