If you designated your 403(b) contributions as after-tax deductions, when you take a distribution of these funds they would not be taxable at that time.

If the distribution is a mixture of pretax and after-tax funds, a percentage of the distribution will be taxable. The percentage would be determined by what percent of the total fund was attributed to after-tax funds at the time of the distribution.

The custodian of your account is not required to make a distinction between the taxable and nontaxable portion of amounts distributed from your 403(b). You must provide that information on your income tax return by indicating the entire amount of the distribution versus the amount that is taxable.

Because you asked that the contributions be made with after-tax funds, none of your contributions to the 403(b) are tax deductible . Your employer will include the amounts deducted in box 1 of your W-2.