A Form 1099-R for an ordinary distribution from a traditional IRA is required to show the same amount in box 2a as is in box 1. When you have basis in nondeductible traditional IRA contributions, the nontaxable and taxable amounts are instead calculated in Part I of Form 8606.
On the page that lists the Forms 1099-R that you have entered, click the Continue button, then, when asked, answer Yes that you made nondeductible contributions to your traditional IRAs, then enter the amount of your basis and your year-end balance in traditional IRAs. With this information, TurboTax will prepare Form 8606, include the gross distribution amount on Form 1040 line 4a and only the taxable amount on line 4b.
