S.D. Codified Laws § 62-4-5
If, after an injury has been sustained, the employee as a result thereof becomes partially incapacitated from pursuing the employee's usual and customary line of employment, or if the employee has been released by the employee's physician from temporary total disability and has not been given a rating to which § 62-4-6 would apply, the employee shall receive compensation, subject to the limitations as to maximum amounts fixed in § 62-4-3, equal to one-half of the difference between the average amount which the employee earned before the accident, and the average amount which the employee is earning or is able to earn in some suitable employment or business after the accident. If the employee has not received a bona fide job offer that the employee is physically capable of performing, compensation shall be at the rate provided by § 62-4-3. However, in no event may the total calculation be less than the amount the claimant was receiving for temporary total disability, unless the claimant refuses suitable employment.
SDCL 62-4-5