<prompt> Human: So Ive been working on a spreadsheet to attempt to compare the difference in returns between a Roth 401k and a regular 401k.It looks like most of the pundits recommending Roth before regular are doing it primarily with the assumption that youre going to put the same amount into each, so the Roth will always grow to be more valuable since you paid taxes on it earlier. Im not doing that, Im assuming a rational investor whos saving the same amount of after tax dollars in either case, so the regular 401k investor is either investing more because of the tax savings, or investing in after tax outside investments. Surprisingly, its starting to look like Roth is always a loser, primarily because of the difference between marginal and effective tax rates. You pay taxes on Roth contributions at your marginal tax rate while working, but you pay taxes on your 401k withdrawals at your effective tax rate. Making effective higher in retirement than marginal while youre working is hard. It looks like thats true only when: you have effectively a zero marginal rate because youre getting the earned income tax credit and paying no taxes you have a lot of taxable income in retirement beyond your 401k withdrawals from pensions and the like you saved so much your retirement income from 401k withdrawals is a lot bigger than your income while workingHas anyone else tried to model this? What do you think?  <response>: I like knowing that my Roth money is now in the free and clear. I never have to pay income taxes on it again, so it doesnt matter how much they increase the tax rates. I also like not being forced to take money out of my investment accounts where theyre making money. 