Earnings for missed deferral opportunity when plan's ROR is negative

[Trisports]

Greetings,

The plan sponsor is required to make a corrective contribution for the missed deferral opportunity. The EPCRS states that if the employee had not made any investment choices, the rate of return (ROR) under the plan can be used. It was my understanding that if the ROR is negative, the IRS underpayment rates must be used but I can't point the Rev. Anyone has the citing for this?

Thanks.