Never. I don't know why TurboTax bothers to ask the question when the code 4 in box 7 already supplies the answer and is what the IRS goes by.
The only case where the question makes sense is for a distribution from a Roth IRA. The code in box 7 for a distribution from a Roth IRA can't be used to distinguish between a distribution from an owed Roth IRA and a distribution from an inherited Roth IRA if the recipient of the distribution was age 59½ or over at the time of the distribution. (Code T or Q is used in both cases.)
