S.D. Codified Laws § 25-7-6.26
If a parent in a child support establishment or modification proceeding fails to furnish income or other financial information, the parent is in default. Income not actually earned by a parent may be imputed to the parent pursuant to this section. Except in cases of physical or mental disability or incarceration for one hundred eighty days or more, it is presumed for the purpose of determining child support in an establishment or modification proceeding that a parent is capable of being employed a minimum of one thousand eight hundred twenty hours per year at the state minimum wage, absent evidence to the contrary. Evidence to rebut this presumption may be presented by either parent.
Income may be imputed to a parent when the parent is unemployed, underemployed, fails to produce sufficient proof of income, has an unknown employment status, or is a full-time or part-time student, whose education or retraining will result, within a reasonable time, in an economic benefit to the child for whom the support obligation is determined, unless the actual income is greater.
In all cases where imputed income is appropriate, the amount imputed must be based upon the following:
Income is not imputed to a parent who is physically or mentally disabled to the extent that the parent cannot earn income; who is incarcerated for more than one hundred eighty days; who has made diligent efforts to find and accept suitable work or to return to customary self-employment, to no avail; or when the court makes a finding that other circumstances exist that make the imputation inequitable, in which case the imputed income may only be decreased to the extent required to remove such inequity.
Imputed income may be in addition to actual income and is not required to reflect the same rate of pay as actual income.
SDCL 25-7-6.26