You clearly have identified a BIG problem. The plan is not following its terms. Participants have a court enforceable right to defer a percentage. The financial advisor is risking law suits and I guarantee HIS employer would not allow him to make that decision as he is taking on a fiduciary role. And for what? I have not seen any payroll software that does not offer a choice of dollar amount or percentage; I doubt it makes any difference to the CPA, and if it does, that's the CPAs problem!