Vanguard, the fund company that oversees more than $3 trillion in assets and that has built its brand largely on its low-cost, passively managed indexed mutual funds, has been cited by Labor Secretary Thomas Perez in public comments and in testimony before Congress as a company that operates with its clients’ best interests in mind.

On one occasion, Perez quoted Vanguard founder Jack Bogle in an interview with CNBC in which he defended Labor’s initiative to craft a new fiduciary standard for all retirement advisors.

“When you put your customers first, that’s not only good for the customer, it’s good for business,” said Perez, quoting Bogle.

But the fund company that may be the standard bearer for the DOL’s vision for the retirement advisory industry going forward has real problems with the agency’s proposed conflict of interest rule.

Specifically, the proposal could “curtail access to important educational and advisory services to (retirement) plans, participants and IRA investors,” wrote Martha King, managing director for Vanguard’s institutional investor group, in a comment letter to the DOL.

“If the Department defines investment advice too broadly, the attendant costs of a fiduciary level of service are likely to result in increased costs to retirement investors for basic investment counseling or even the termination of important investor services,” added King.

As proposed, the rule would classify common investment conversations and “generic communications” as fiduciary advice.

The due diligence requirements under the proposal’s Best Interest Contract Exemptions could impose cost increases on providers, and that could result in the elimination of services, even in instances where clients have no reasonable expectation of a fiduciary level of care, said King.

King said Vanguard wants to see a substantially simplified Best Interest Contract Exemptions, a more specific definition of fiduciary advice, and clearer carve outs for investor education.

Only individualized communications should qualify as investment advice, thinks Vanguard.

And the question of how investments are valued should be a part of a separate rulemaking process. Under the proposal, the DOL seeks to clarify the role of fiduciaries that value private companies in ESOP offerings.