Click the Continue button on the page that lists the Form 1099-R that you have entered and, when asked, enter your basis in Roth IRA contributions and, if any, Roth conversions. TurboTax will prepare Form 8606 to calculate the taxable amount of your distribution and, if your basis in Roth IRA contributions is more than $8,000, the taxable amount will be $0. With $0 being taxable, the $8,000 will be included on From 1040 line 4a but will be entirely excluded from the taxable amount on line 4b.
