Calculation is client-side, income figures are never transmitted or stored.
How South Dakota Child Support Is Calculated
- Add both parents' net monthly income to get combined income, then look up South Dakota's Support Obligation Schedule for the total number of children.
- Each parent's share of that amount is their percentage of combined net income.
- If the obligation computed from the paying parent's OWN income alone (looked up in the schedule directly) is lower than their prorated share of the combined-income amount, the LOWER figure applies -- this is South Dakota's Self-Support Reserve mechanism, built directly into the schedule's 'emboldened areas.'
- Above $20,000/month combined net income, the schedule does not extend automatically -- the obligation is set case-by-case considering the child's needs and standard of living.
South Dakota Child Support Worksheet Walkthrough
Example: Parent A has net monthly income of $1,200, Parent B has net monthly income of $1,300 (combined $2,500). There are two children, who live primarily with Parent B.
- Combined net monthly income: $1,200 + $1,300 = $2,500.
- Support Obligation Schedule at $2,500 combined, two children: $890.
- Parent A's income share: $1,200 / $2,500 = 48%. Prorated share: $890 x 48% = $427.
- Individual lookup using Parent A's own income ($1,200) alone, two children: $359.
- Since $359 is lower than $427, the Self-Support Reserve applies: Parent A pays $359/month.
How This Calculator Works — Formula & Constants
Source: South Dakota Department of Social Services — SDCL 25-7-6.2 · 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
Deterministic calculation based on South Dakota's official guideline schedule table. Verify against South Dakota's official calculator for a court-ready figure.
FAQ
How is child support calculated in South Dakota?
Add both parents' net monthly income to get combined income, then look up South Dakota's Support Obligation Schedule for the total number of children. Each parent's share of that amount is their percentage of combined net income. If the obligation computed from the paying parent's OWN income alone (looked up in the schedule directly) is lower than their prorated share of the combined-income amount, the LOWER figure applies -- this is South Dakota's Self-Support Reserve mechanism, built directly into the schedule's 'emboldened areas.' Above $20,000/month combined net income, the schedule does not extend automatically -- the obligation is set case-by-case considering the child's needs and standard of living.
What is South Dakota's Self-Support Reserve?
SDCL 25-7-6.2 compares two figures for lower-income paying parents: (1) the standard prorated share of the combined-income schedule amount, and (2) the schedule amount looked up using the paying parent's OWN income alone. Whichever is LOWER becomes the child support order -- this protects paying parents with limited income from an obligation that exceeds what their own income alone would produce.
Does South Dakota use gross or net income?
Net income. South Dakota's Support Obligation Schedule (SDCL 25-7-6.2) is indexed by combined monthly NET income for both parents.
How does shared parenting time affect South Dakota child support?
South Dakota has a separate Shared Parenting Child Support Obligation Worksheet for cases where both parents have substantial parenting time, which uses a different calculation than the standard primary-custody worksheet this calculator models.
Methodology & Source
Formula model: income shares. Effective 2021-07-01, guideline version 2021-SD-v1, last reviewed 2026-07-13.
Official source: South Dakota Department of Social Services — SDCL 25-7-6.2 (SDCL 25-7-6.2).
SDCL 25-7-6.2: if the obligation computed from the paying parent's OWN monthly net income alone falls within the schedule's emboldened (self-support-reserve) areas, that amount is compared to the standard combined-income-prorated amount, and the LESSER applies. This calculator models the standard (primary-custody) case only -- it does not model South Dakota's Shared Parenting Child Support Obligation Worksheet (used when both parents have substantial parenting time) or Split Custody. Above $20,000/month combined net income, SDCL 25-7-6.2 does not provide an automatic extension -- the obligation is established at an appropriate level considering the needs and standard of living of the child, determined case-by-case.
Guideline figures transcribed from the primary source above and cross-checked against South Dakota's official calculator/worksheet for multiple test scenarios — see our verification methodology.