To obtain the maximum lump sum under 415, what rate do I use.
I have an EOY val, plan year 3/1/2000 - 2/28/2001.
The way I understand it, I should be using the GATT rate in effect as of the first lookback month (which I am thinking is 6.23% the February 2000 rate).

The document will state both the lookback period and the stability period. If lookback is 0 or 1 mo. and stability is plan year, then the rate for Feb 2001 is what would be used, or actuarial equivalent if higher. Also must know what happens with any grandfathered benefit on the switchover - may be any of three methods for disposing of old accrued benefit.