Child Support and Custody in South Dakota: How Parenting Time Affects Your Obligation

The Income Shares Model

South Dakota calculates child support under the Income Shares model, codified in SDCL Chapter 25-7. The basic idea: both parents contribute to the child's financial support in proportion to their incomes.

The calculation starts with each parent's monthly net income. You combine those figures and look up the basic child support obligation on the statutory schedule. Then you divide that obligation based on each parent's percentage of the combined income. The parent without primary custody pays their share to the custodial parent.

For example, if the combined monthly net income is $6,000 and Parent A earns 60% of it, Parent A is responsible for 60% of the basic support obligation.

The 180-Night Cliff

This is where custody and child support intersect in a way that creates real financial consequences: South Dakota has two entirely different support calculation formulas, and which one applies depends on whether a court-ordered shared parenting plan meets the 180-overnight threshold and the other conditions for the cross-credit.

Below 180 nights with the noncustodial parent → standard primary custody support. The noncustodial parent pays their income-proportionate share of the basic obligation, potentially reduced by a parenting time abatement.

At or above 180 nights each under a court-ordered shared parenting plan, with both parents' written agreement to share parenting duties, responsibilities, and expenses in proportion to their incomes → the shared parenting cross-credit formula under SDCL § 25-7-6.27. This formula accounts for both parents' duplicated household costs and typically produces a significantly lower net support payment.

The difference between 179 and 180 overnights can be hundreds or thousands of dollars annually. That one night doesn't change the child's needs — but it can change which formula applies.

The Parenting Time Abatement

If the noncustodial parent has the child for at least 72 overnights per year (6 or more per month) under a valid court order, they may qualify for a parenting time abatement under SDCL § 25-7-6.14.

The abatement reduces the basic child support obligation by 38% to 66% for those overnight periods, depending on the parent's demonstrated increase in non-duplicated expenses — clothing, school supplies, activity costs — during their parenting time.

Two important catches:

1. The burden of proof is on the noncustodial parent to show the increased expenses. You need documentation, not assumptions.
2. If you receive the abatement but fail to actually exercise your court-ordered parenting time during a calendar year, you must repay the entire abated amount to the custodial parent. The abatement is contingent on actually spending the time with your child.

The Shared Parenting Cross-Credit Formula

When both parents have the child at least 180 nights per year under a court-ordered shared parenting plan, and agree in writing to share parenting duties, responsibilities, and expenses in proportion to their incomes, support is calculated using a five-step cross-credit formula:

Step 1: Take the basic combined child support obligation from the statutory schedule and multiply by 1.5. The multiplier accounts for the duplicated costs of maintaining two fully equipped homes.

Step 2: Multiply the result by each parent's income percentage to get their individual shared obligation.

Step 3: Prorate each parent's obligation by the percentage of nights the child spends with the other parent (divide the other parent's nights by 365).

Step 4: Offset the two prorated amounts. The parent with the larger prorated obligation pays the difference to the other parent.

Step 5: The court checks whether the resulting offset would substantially harm the child's standard of living in the lower-income parent's home. If so, the court can deny the cross-credit.

Imputed Income

If a parent is voluntarily unemployed or underemployed, the court must impute income under SDCL § 25-7-6.26. The default imputation is the state minimum wage ($11.85/hour as of January 2026) multiplied by 1,820 hours annually — producing a gross monthly income of $1,797.25.

The presumption is that every parent is capable of earning at least minimum wage. A parent who quits their job to reduce their support obligation will find the court calculating support based on what they could earn, not what they choose to earn.

Healthcare and Childcare Add-Ons

Beyond the basic support obligation, the court allocates:

Medical insurance. If accessible insurance is available to either parent at a reasonable cost (8% or less of their monthly net income after credit), that parent must maintain coverage. Premium costs are split proportionately by income.

Uninsured medical costs. The parent with primary physical custody covers the first $250 per child per year in uninsured costs (copays, dental, vision, counseling). Costs above $250 are split by income percentage.

Work-related childcare. Daycare and after-school care costs necessary for employment or education are split by income percentage, net of any federal childcare tax credits.

Making the Connection Between Schedule and Support

When you're drafting your parenting plan, count the overnights. A schedule that puts you at 175 nights vs. one at 185 nights isn't just about five extra evenings — it's the difference between two entirely different financial formulas. That doesn't mean you should negotiate parenting time as a financial strategy, but you should understand the math before you agree to a schedule.

The South Dakota Child Custody & Parenting Plan Guide includes a child support estimation worksheet that walks you through both formulas — the standard abatement model and the shared parenting cross-credit — so you can see the financial impact of different schedule options before you finalize your plan.

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