When you've entered your basis in nondeductible traditional IRA contributions as you have done in this case, TurboTax tracks the basis on TurboTax's IRA Information Worksheet. TurboTax is transfers in the information from this worksheet when you transfer in your previous year's tax file to begin your tax return.
You'll need to track your basis until you no longer have any funds in traditional IRAs at the end of some year. At that point, all of the basis will have been distributed. Keep your Forms 8606 forever to document your basis history.
