Modeling 401-k after-tax contributions and balances
The 401-k after-tax balance should be entered into the "ROTH accounts" totals based on prior questions. This does address the tax exemption on withdrawal but does not address the taxable gains since ROTH balances are tax exempted.
For after-tax contributions, I'm assuming they are also entered on the contribution tab as "ROTH" since contributions are not tax exempt. Again, the gains on these contributions should be taxed upon withdrawal.
Is this the "best" way to handle it? I can't think of a way to correct the under taxation since everything is rolled into a single ROTH balance and real ROTH accounts are also involved.