I addressed all of this accurately in my precious reply. "Elective deferrals" in the traditional 401(k) account are always pre-tax money taken from your pay and are excluded from box 1 of your W-2. Earnings in the traditional account are also pre-tax. If the plan permits, you can also make after-tax contributions to the 401(k) from your pay, money on which you are taxed and is not excluded from box 1 of your W-2, but these after-tax contributions are not elective deferrals.
If the plan allows after-tax contributions, these are kept in a separate sub-account of the traditional 401(k) account. An In-plan Roth Rollover can be done on just this sub-account, independent of the other funds in the traditional 401(k) account, and if done immediately will consist entirely of the nontaxable after-tax funds. The result will be that the amount will be included in boxes 1 and 5 of the Form 1099-R and box 2a will contain a zero. This is the so-called Mega Backdoor Roth which, @srr , is apparently what you have been doing.
So the answer to TurboTax's question that asks if the amount rolled over included after-tax funds depends on the particular circumstances of the In-plan Roth Rollover. Nowhere did I say otherwise.
