The traditional IRA contribution and the Roth conversion are entirely separate entries in TurboTax. A nondeductible traditional IRA contribution adds to that basis on Form 8606 line 1 and the Roth conversion consumes some of that basis, also calculated on Form 8606 Part I. The amount of basis that is applied to make a portion of the Roth conversion nontaxable is an amount in proportion to the overall balance in your traditional IRAs.
