Question: what is the maximum after tax 401k contribution?
Answer: After-tax 401(k)'s are not subject to the 2020 federal maximum of $19,500. Instead, they're subject to the overall plan maximum of $57,000. Meaning, if you've maxed out your traditional or Roth 401(k) contributions at 19,500, you're still able to contribute up to $37,500 to the after-tax account!