S.D. Codified Laws § 58-17-2.3
No insurer or health carrier issuing health insurance coverage, other than excepted benefits, that provides dependent coverage for any qualifying child, as defined by rules promulgated pursuant to § 58-17-87, may terminate coverage due to attainment of a limiting age below age twenty-six. If the dependent remains a full-time student upon attaining the age of twenty-six, but not exceeding the age of twenty-nine, the insurer shall provide for the continuation of coverage for that dependent at the insured's option. However, the provisions of this section do not apply to any qualifying relative, as defined by rules promulgated pursuant to § 58-17-87, whose gross income is less than the exemption amount as prescribed by the director by rules promulgated pursuant to chapter 1-26. Continuation of coverage for full-time students attaining the age of twenty-four is not required if the dependent has other creditable coverage in force nor required for any full-time students who attained the age of twenty-four prior to July 1, 2007.
SDCL 58-17-2.3
SL 2011, ch 216, §19 provides: "The provisions of this Act are repealed if the Patient Protection and Affordable Care Act, Pub. L. No. 111-148, 124 Stat. 119 (2010), as amended by the Health Care and Education Reconciliation Act of 2010, Pub. L. No. 111-152, 124 Stat. 1029 (2010) is found to be unconstitutional in its entirety by a final decision of a federal court of competent jurisdiction and all appeals exhausted or time for appeals elapsed."