<prompt> Human: Im hoping for somebody to poke a hole in my thinking. Ive historically only contributed to a traditional 401k and now Im considering doing half in ROTH 401k. Right now my traditional 401k contributions of 18,500year are saving me 4070in taxes. Once my wife starts working Ill save 4440in taxes24 top bracket for me and 4440 for her when she maxes her 401k out too. Assuming Im going to contribute the same effective value to either 401k option, it looks like this: My 401k will yield: 18,500, 5 interest rate, 35 years1,758,773If I take the 4440 saving in taxes and invest that in a brokerage account, it will yield 422,105.ROTH 401k will yield 1,758,773. Now once Im retired and lets say I want 100kyear. For Roth, its simple, I dont pay taxes and 100kyear will last me 17.59years. For traditional, the 401k will be taxed as income, and using todays tax tables, that will put the rate at 17.3. The brokerage will be taxed as capital gains at 20. Using a weighted average with the different balances, I get a tax rate of 17.8. That means I need to withdraw 121,700 to get 100,000year. This will last 17.92years. If I use a 32 current top tax bracketincome between 315,000-400,000, then the traditional brokerage will get me 100kyear for 19.08 years. If you do this same exercise with the 24 bracket and assume you only need 77kyear in retirement, then the traditional 401k makes more sense as it will last you 24 longer than the Roth. The above calculations assume that we have the same tax bracket setup in 35 years. It seems like there is a slim chance that we have the same setup and with the traditional barely edging out the Roth, I feel like Id rather have my money in the Roth. Unless they impose a tax on Roth accounts, Id feel better about a bucket of money that isnt subject to a change in tax policy like the traditional and the brokerage would be. I also like the idea of being in retirement and having two different buckets of money to withdraw from where one bucket is subject to taxes and one isnt. I think I want half of our money in traditional and half in Roth. Also, I know Im only looking at one retirement account when in reality my wife and I have 4 but I think the logic applies to her 401k as well. Bg info: 26. Married. No kids. My Salarybonus 170kWife-student, will be making 120k starting in 2019.Current balances:401k: 130,000Roth IRA: 26,000Wife Roth IRA: 10,000Brokerage: 16,000Savings: 10,000Emergency:15,000No debt besides small mortgage. 100kTLDR: Im going to start contributing to ROTH 401k since there isnt that much of a difference.  <response>: One thing I didnt realize until a few years ago is that that even though all money I put in my Roth 401k is tax free later, my employer match is a safe harbor contribution and subject to tax. So I suppose Im already a bit diversified in my retirement tax status. 