If I change funding method from Individual Aggregate to EANC, Rev Proc 2000-40 says the new unfunded is amortized over 10 years. This means that the minimum and the maximum are the same for the first year of change. Since gains/losses are amortized over 5 years (if I am not mistaken), for years that there are losses, the minimum is greater than the maximum, in which case the minimum applies. Is this correct or is there something wrong with my reasoning? If this is correct, is there a way to get a contribution range if you want to change from Individual Aggregate (at least in the first year)?

Correct, but that is not new, as we have often had the minimum override the maximum.

Don't forget about the credit balance. It can exist under the IA or Agg method, and is usually the way in which the minimum is less than the maximum. If you have one, suggest the sponsor hang on to it. Without a credit balance, I'm not sure you have any options for getting a range.

Thanks. I was hoping you would say otherwise. My brain is still accustomed to the initial base being amortized over 30 minus the number of years the plan has been in effect. Oh well......

Don't forget the unfunded current liability deduction. That could give you a range.