An individual is employed by a governmental agency. The individual participates in a PERS deferral plan as well as a Section 457 plan as a government employee. The individual also has a separate business which he operates and participates in a Simple Plan. Question: What Annual Addition Limits (if any) apply to this individuals participation in the three (3) plans?

The limitations apply on an employer basis. So you would need to aggregate all plans of employers which are required to be aggregated under IRC 414. In this case it would seem unlikely that the non-governmental employer would be required to be aggregated. However there are no regs out, in general, on how to determine ownership, etc. of governmental agencies, etc. If it could be shown that the individual controlled the governmental agency, then there might be aggregation. There is some mention of this in regards to IRC 403(B) plans.