As far as I can tell, almost nothing has changed over the years with regard to how TurboTax handles the carryforward of basis. I haven't tested it recently, but I suspect that TurboTax will still silently erase any carryover basis (Form 8606 line 2) if you mistakenly tell TurboTax that you did not make nondeductible traditional IRA contributions. However, I think in the past TurboTax would not allow you to reenter the erased amount without explanation, but now TurboTax does not require explanation if the amount reentered is the same as the amount erased.
