Existing MP plan with 1-year eligibility with rich formula with mostly doctors but a few employees. There is enough room under 25% deduction cap (404(a)(7) to add-on a modest DB plan for doctors only and still pass 401(a)(26), 410(b), and "maybe" 401(a)(4) depending on response to this quiry. The doctors would like the DB plan to have a 2-year wait to delay newly hired physicians into the plan. If both plan have different waiting periods can I still aggregate plans for 401(a)(4) general test for discrimination ? If so, do I use the 2-year wait and treat benefits earned before the 2-year wait (under the MP plan) as a disaggregated plan ? Thanks for any thoughts/opinions.

You can still aggregate the plans even though there are different waiting periods. However, when determining nonexcludables for the group only those that meet the LESSER of the two eligibility requirements will be nonexcludable for nondiscrimination.