post termination amendment of plan

[Guest SVogel]

We are terminating a defined benefit plan which has been submitted to the PBGC and the the 60 day period has expired. We are not submitting plan to IRS. Client has determined that cost of providing annuities is too expensive and now wants to amend the plan to allow lump sums elections. Pursuant to PBGC instructions, as long as we are not taking anything away, a post termination amendment is ok. However, my understanding is that the IRS has taken the position that once the termination date is past, the plan cannot be amended other than to implement required interim amendments. Can anyone comment on whether or not this is the case and possibly provide a citation?