When you have basis in nondeductible traditional IRA contributions, TurboTax performs on Form 8606 the calculation of the taxable amount determined from your basis, the amount distributed or converted and the amount remaining in your traditional IRAs at year-end. Make sure that you click the Continue button on the page that lists the Forms 1099-R that you have entered so that you reach the page that asks you to enter or confirm your basis and the page that asks you to enter your year-end balance. TurboTax will include the entire $40k on Form 1040 line 4a but will include on line 4b only the taxable amount from Form 8606 line 18.
Because the calculation of the taxable amount must be performed on Form 8606, TurboTax cannot ask you to provide the taxable amount.
Your numbers suggest that you converted half of your traditional IRA funds to Roth, so an $18k nontaxable amount implies that your basis in nondeductible traditional IRA contributions was $36k. That's what you should see on Form 8606.
When you have basis in nondeductible traditional IRA contributions, TurboTax performs on Form 8606 the calculation of the taxable amount determined from your basis, the amount distributed or converted and the amount remaining in your traditional IRAs at year-end. Make sure that you click the Continue button on the page that lists the Forms 1099-R that you have entered so that you reach the page that asks you to enter or confirm your basis and the page that asks you to enter your year-end balance. TurboTax will include the entire $40k on Form 1040 line 4a but will include on line 4b only the taxable amount from Form 8606 line 18.
Because the calculation of the taxable amount must be performed on Form 8606, TurboTax cannot ask you to provide the taxable amount.
Your numbers suggest that you converted half of your traditional IRA funds to Roth, so an $18k nontaxable amount implies that your basis in nondeductible traditional IRA contributions was $36k. That's what you should see on Form 8606.