Originally Posted by Gazingus
Will my 72t rate be locked in for the five years of my SEPP?
The short answer is yes. If you look at a 72t calculator you will notice there are 3 distribution methods to choose from, required minimum, amortization, and annuitization. The minimum distribution method is determined by dividing your account balance by the value in the life expectancy table for your age. It is recalculated every year but it also has a much lower initial payment so if you are looking at getting the maximum distribution allowed it's usually not the best choice. Both the amoritization and annuitization methods interest rates are locked in but do allow a one time switch to the required minimum method. I believe the main reason the IRS allowed this switch was so one could avoid draining their account of funds if their investments took a dive.
As others suggested you need to be very careful when setting a 72t up. Don't take what I or anyone else says as gospel. Study up on the IRS 72t documents and as was recommended 72t.net is a good source.