Assume you have separate 401(k) plans for the same employer that each pass 410(b). What provisions of the Plans need to be the same? I can think of:

1) Availability of catch-up contributions

2) Limitation Year

3) Top-Paid group election

4) Calendar Year election

5) Testing methodology (current year or prior year) but only if you think you might need to aggregate the plans in the future.

Anything else that you can think of?