S.D. Codified Laws § 3-13-72
Establishment of accounts--Specified contributions--Recordkeeping
No contributions other than a designated Roth contribution and a properly attributable investment return may be credited to a participant's designated Roth account. The plan must maintain separate recordkeeping for each designated Roth account and must record the year that the participant first made a designated Roth contribution.
Source: SL 2025, ch 27, § 99.