Plan to Plan Transfers

[30Rock]

I have a plan to plan transfer question. EIther an employer based transfer or a participant elected transfer, as permitted under the final 403bn regs. I understand, I think, the rules regarding a custodial account funded plan transfer, in that you have to restrict the employer contributions upon transfer so no in service are allowed prior to age 59 1/2. But what happens when an ERISA plan funded with an annuity contract under 403(b)(1) is transfered to a plan funded with 403(b)(7) custodial accounts and the annuity has more liberal in service w/d's of employer contributions - i.e. age 40 and the 5 year/2 year distributions? Do they have to be preserved, or can the funds fold into the custodial account and become subject to these more restrictive withdrawal rules? WHat about a vesting schedule - assume more generous vesting must be grandfathered?

Thanks!