我是这样算的

let's say the overfunding amount is $6000. The penalty is $600. He needs to pay tax, say 35%, when he takes money out of 401K, that is $2100. So he loses $2700 which he will not pay if he just keeps this amount of money in the bank. In the meantime, he is able to get $6000 from his employer. Certainly, he needs to pay 35% tax for this $6000 when he takes money out, which is $2100; but he still gains $3900, which is more than the $2700 he loses.