PA taxes all compensation when earned, so deferred compensation(401k, 403b, 457b) during the year is not taxed federally but PA taxes it each year. Those are therefore after-tax contributions.

When receiving distributions, federal taxes all distributions when received SINCE FEDERAL NEVER TAXED CONTRIBUTIONS NOR EARNINGS ON THE RETIREMENT ACCOUNT.

Not PA. Since PA taxed the contributions when earned, PA doesn't tax the distributions. They also do not tax the earnings that are part of the distributions.

Estate 1041s are merely income tax returns that tax income that would otherwise be taxed to people on 1040s, but since the TP died, somebody else has to pay the income tax on taxable income.

Many other states tax retirement income(not after-tax monies, though), like NJ. PA does not, except when distributions are made before age 60 and the interest from annuities.

Is box 16-1 on 1099-R completed?