457 and Catch-Up Contributions

I have a client that recently came to us with a 457 Plan (deferral only) and from what I can see, they are a 501(c)3 non-profit. At this point, I do not know if they have any government funding or oversight. The Plan has allowed catch-up contributions for the last several years. My knowledge may be limited, but I think catch-ups are only allowed on government entity plans. Does anyone know if this is that black and white, or if there are any other factors they may be relevant?

Age 50 catch-up provisions can be written into a 457(b) plan only if the plan sponsor is a government. The special “last 3 years” catch-up provisions can be written into any 457(b) plan regardless of the type of plan sponsor. No gray area there. 

Agree with John Feldt.  Further, allowing an age 50 Catch Up  in a 457(b) sponsored by a 501(c)(3) org disqualifies the plan if it is not returned by the next April 15.  No exceptions and no correction program now available.  All the money in the plan is taxable.  This plan is disqualified.