The basis of your Traditional IRA is the sum of nondeductible contributions you made through the years. Your 401(k) would have no basis as all contributions were from pre-tax money. If all your IRA contributions were deductible, then you have no basis in your IRA.
But TurboTax will automatically generate form 8606 for the conversion to a Roth IRA. As you have no basis, the whole amount converted is taxable.
Please read this TurboTax article for more information.
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"
