SEP and Combo

A prospective client wants to adopt 401K/PS/Cash Balance combo for the 2024 plan year. However, they already made the SEP contributions for the 2024 plan year. Is it possible for them to adopt the combo strategy? If so, how does the NDT work with the SEP contributions? Where can I find more information on this?

TIA

If SEP is on 5305-SEP model then not possible for 2024. If SEP contribution was more than 6% of eligible payroll and the CBP will be PBGC-exempt then you have the 31% combined plan deduction limit. If there are employees, I do not think you can aggregate SEP with CB for coverage and nondiscrimination, nor count any SEP contribution toward gateway. I cannot find a cite but a Google search gave me an AI-generated answer that SEP does not count toward gateway.