Thanks for that info. It helps me to understand but I still think the math doesn't add up. If I enter it the way you're suggesting, leaving box 2 a blank and *not* checking that box 2b "taxable amount not determined box is checked", which seems to be right, and then answering the rest of the questions correctly. including indicating that I'm now at MRA, my refund is 6K higher than if I enter the full amount from box 1 in box 2a (around 30K). So it seems that doing it the suggested way results in that entire 30K being untaxed, given that 6K difference, and I know that isn't right since it's only supposed to be a small difference between the full amount and the taxable amount.
