Although the change to the tax code makes it possible for SEP plans to offer the option for the contributions to be Roth contributions, SEP plans are not required to offer the option. Unless the SEP plan agreement offers the option, a Roth SEP contribution is not permitted to be made.
Correction: If the SEP plan is established using Form 5305-SEP, the employer can offer Roth SEP contributions before Form 5305-SEP is updated
IRS Notice 2024-02: https://www.irs.gov/pub/irs-drop/n-24-02.pdf
