Codes 2 and B together indicate a distribution from the designated Roth account in the TSP, not a distribution from a Roth IRA.
TurboTax unnecessarily asks if this distribution is from a Roth IRA even though the code B in box 7 unambiguously indicates that it is not a distribution from a Roth IRA. This question is nothing more than a trap for the unwary and has caused nothing but problems since answering that the distribution is from a Roth IRA will cause TurboTax to later tell you that you've made an entry error without providing any useful information as to the nature of the error.
