<prompt> Human: I was looking at my new pay stub after my salary doubled and Im getting 500 less than I thought Id be getting, I suppose due to the different tax brackets. I made 2kmonth take-home before my salary increase and now my take-home is 3.5kmonth when I anticipated 4k. Now I think that the more you invest in your Roth 401k, you can reduce your income taxes by a significant amount, thus increasing your take-home income. How do I calculate what percentage I need to have deducted to make an optimal amount of take-home pay?  <response>: Oof. Several things are wrong.First of all, thats not how tax brackets work. Marginal tax brackets means that, while you do pay more taxes based on how much more you make, that higher bracket is only effective on the dollars over your previous bracket. More on thisSecond of all, retirement contributions will never increase your take home pay, because instead of coming home, its now going inside your retirement. This doesnt mean you shouldnt contribute to retirement, but Im just telling you that youll never see a bigger paycheck by doing so.Third and finally, Roth is a post-tax contribution, which then saves you taxes on growth and withdrawals. Traditional 401k or IRA is the tax benefit youre looking for, where contributions reduce taxable income. 