From my understanding, this is not correct. 401K contributions reduce your marginal tax rate. So if you make 100k and contribute 15k, you save about 24% in ta

From my understanding, this is not correct. 401K contributions reduce your marginal tax rate. So if you make 100k and contribute 15k, you save about 24% in taxes. Then when you withdraw 100k a year during retirement, you pay only 18% in taxes. On top of that, since you are only feeling a 11k reduction in your paycheck per year, but investing 15k, you end up with that much higher growth overall starting with a higher base. The only time expected retirement withdraw rate (treated as income at that time) matters is when choosing between Roth and traditional 401k / IRAs. In that case, with Roth you are contributing a lower amount initially (11k reduction in pay = 11k invested, instead of 15k invested), however the interest grows tax free. So if you are investing enough that the interest gives you a huge amount of money during retirement such that your annual retirement income (using 4% rule) gives you much higher pay, you would be better with Roth. But in no case are you better without any tax advantaged account.