我的401K在Fidelity有一個累積表格，列出不同的%，比如 before-tax 60%，after-tax 30%， company match 10%。他們給你錢的時候扣稅，公式可能是這樣：
比如設定每個月拿5000，無形說 after-tax traditional 增值部分交，假設那年總增值10%，那應該是：5000 x 10% x 30% x 0.24 （我的稅率）+ 5000 x 60% x 0.24，一共稅 $756, 拿到的現金是$4244。
Roth，本金增值都不要交。
下麵檸檬說：Top tax rate is 24%, not the effective tax rate，我還沒明白這句話的意思。
- Pre-Tax (Traditional) 401(k):
Contributions made with pre-tax income will result in a tax deduction for
the amount contributed. Contributions are not counted as income, and they
will lower your tax bill come April. When you contribute pre-tax, you are
allowing your assets to grow on a tax-deferred basis. By the time you
retire and begin to pull money out of your account, every dollar withdrawn
(including the growth) is taxable as ordinary income. - After-Tax (Roth) 401(k): Roth
contributions are the opposite of pre-tax contributions. While this option
may not have been widely available in the past, many retirement plans now
offer it. When you contribute to these accounts, you won’t receive a tax
break, but all growth and qualified1 future withdrawals are tax-free. Because you
already paid taxes on this money when you contributed to the account, you
won’t be taxed on this money when you withdraw it in the future
