Why do you locate the command buttons (back, next) at the bottom of the page and not the top? It would simplify navigation if the buttons were always in the same location

[abaione]

At the bottom, as a function of page length, these buttons are not in the same location on each page (as they would be if located at the top of the page).  

Having the buttons at the same location on the screen facilitates navigation, especially when you complete a section and want to move backward to make a simple change and then move forward. 

[CherylW]

It would, I agree, but the reason they're not in the same place is that Turbo Tax asks you questions that must be answered for compliance, and we want to make sure you read and answer them correctly, not just speed by them.

Also, sometimes the user might accidentally click twice, completely bypassing what could be a really important question.