<prompt> Human: Hi PF,Ive been working to improve my personal finance recently. One of the things Ive been playing around with is saving a lot for more retirement. Currently, I have a small percentage of my income going to a Roth 401k. I plan to change this to a larger percentage, making it the annual max. I read that regular 401k contributions are not included in taxable income. If for example I make 55k and contribute 18k to my 401k, my taxable income is 37k, and my marginal tax rate is 15.If I did the same thing, but contributed instead to a Roth 401k, what happens? Does my taxable income remain at 37k, and I get taxed at a marginal rate of 15? Does the Roth 401k contribution get taxed at a marginal 15? Or would my taxable income be on 55k?Sorry if my terms are messed up. I am still fairly new to all this.  <response>: Contributing to a Roth 401k or a Roth IRA does not affect your taxable income. If you make 55k, you get taxed on the 55k. It will not change due to your Roth contribution. 