It's doubtful that in previous years your pension was reported as Roth, although it might have been treated as nontaxable. You can cause an otherwise taxable pension to be treated as nontaxable by misusing the Simplified Method. Since you say that the entire pension should be taxable, you should not be using the simplified method at all. You should just tell TurboTax that either the amount shown in box 2a of the Form 1099-R is the taxable amount or, if box 2a is blank, that you made no after-tax contributions and the entire amount is taxable.
