"The increased flexibility of this retroactive plan amendment self-correction option, coupled with the extension of the two-year self-correction period for significant operational failures to a three-year period, is a boon for plan sponsors looking to correct operational failures under their plans and that ... otherwise would have been required to submit a formal application to the IRS under the Voluntary Correction Program (VCP) -- including the payment of a VCP user fee of up to $3,500 -- to obtain the IRS's approval of a proposed correction."