Cash-Balance Plan

[JAY21]

Do we currently have a design-based safe harbor formula for a cash-balance plan ? Did the final and proposed regs add anything to this issue ? The 401(a)(4) regs under section 1.401(a)(4)-8© has a safe-harbor structure but some of the requirements seem outdated and would not allow you to take advantage of the more recent evolution of cash-balance plans (i.e., these regs require the accrued benefit to be the actuarial equivalent of the hypothetical account balance, require if you use a fixed interest rate that it produce the same present value as 417e rates).

I have a simple cash-balance design of 25% of pay for each eligible participant. Under a DC money purchase plan this would be a very vanilla safe-harbor formula, it is such for a cash-balance plan ? or do I need to go through the mechanics to general test it if I want the accrued benefit to be equal to the hypothetical account (not equal to the actuarial equiv. of the hypothetical account) ?

Thanks for any opinions.