South Dakota uses the South Dakota Child Support Obligation Schedule (SDCL 25-7-6.2) to determine child support obligations. Under the Income Shares model, both parents' incomes are combined to estimate what the family would have spent on the child if the household were intact. The obligation is then divided proportionally based on each parent's contribution to combined net income.

South Dakota has several distinctive features in its child support system. South Dakota uses net income (after taxes) for calculations. The state includes a specific "extended visitation" credit for parents with more than standard time. South Dakota has one of the lower self-support reserves, reflecting the state's lower cost of living.

South Dakota bases calculations on net income — meaning income after mandatory deductions like taxes, Social Security, and Medicare. This gives a more accurate picture of each parent's take-home pay. The self-support reserve in South Dakota is $1,175/month, ensuring the paying parent retains enough income to cover basic living expenses.

South Dakota recognizes "Extended Visitation" when the non-custodial parent has the children for at least 128 overnights per year (approximately 35% of the time). When this threshold is met, the standard child support formula is adjusted to reflect the increased direct expenses borne by both parents.

Under South Dakota's Income Shares approach, the shared parenting adjustment typically calculates each parent's obligation based on their income share, then applies a credit or cross-calculation that accounts for the time each parent directly supports the child. The more overnights the non-custodial parent has, the greater the reduction in their payment — but the adjustment is not dollar-for-dollar because fixed costs like housing don't decrease when the child is away.

Below 128 overnights, South Dakota generally treats the arrangement as a sole custody situation with standard visitation, and no custody time adjustment is applied to the child support calculation.