If an employer has two plans (such as a money purchase plan and a profit-sharing plan), how do the 415 limits, the limits on deductions, the 417 limits, and so forth apply? I know the usual limits on annual additions usually amount to 100% of compensation and approximately $42,000 (annually adjusted limit, of course), but I had not given much thought about how this applies if an employer has more than one plan.

If they are both defined contribution plans, such as in your example the limits for 404 and 415 are applied to the combination (or totals) of both Plans. If you take all of the rest of the limits one at a time, they are easy.
402(g) Limit of 15,500 plus catch up is per person and all Plans combined.
417 limits the amount of compensation used in calculating benefits and testing...this is on a per Plan basis and you do not need to cut it in half because you have two plans.


Oh. Top heavy would also be combined. What I mean is that in calculating whether the plan is top heavy, you would use all balances in both Plans Plus distributions from both Plans. Then, if the Plan is Top Heavy, you would need to meet the TH minimum once. The Plan documents should be coordinated and tell you which Plan needs to provide the TH minimum.