CuseFan, there can be circumstances in which fees might relate to shared or coordinated services, with an experienced fiduciary’s prudent attention to protective conditions and reasoned accounting.
But in the situation your opening post describes, wouldn’t a good fiduciary ask the service provider whether it would charge the employer a regular fee for the payroll service, and lower the fee charged to the retirement plan?
Does the service provider’s offer of “free” payroll services suggest that the retirement plan’s fiduciary might not have selected or negotiated the best deal the plan could obtain? (Whether with the same provider, or by selecting a different provider?)
When one fee otherwise would burden the employer and another fee burdens the plan, shouldn’t whatever combined fee lowering is available favor the entity the ERISA-governed fiduciary owes its exclusive-purpose loyalty to? And shouldn’t the retirement plan’s assets not benefit an entity about which the plan fiduciary might, even indirectly, have a compromising interest that could interfere with the plan fiduciary’s unimpeded decision-making for the plan’s benefit?
Observe that the conflict might be less (but not completely removed) if the employer pays the retirement plan’s fees from the employer’s assets, with nothing charged to the plan.
I concur with your observation that one might not call out a seeming breach, at least not without having collected and analyzed the facts. (Even if I saw an obvious breach, I wouldn’t say anything other than to my client.)
Knowing that many plan fiduciaries do not get a lawyer’s advice (even when the retirement plan properly could pay that fee) motivated my question:
What percentage of small-business employers innocently do not know that it is improper to allow a retirement plan to subsidize a lowered expense for some other service?