<prompt> Human: I currently max employer 401k and a Roth IRA. Im interested in FI and opening an additional traditional 401k through Vanguard and letting the Roth sit and grow for the next 20 years.My question is, how is the traditional 401k being contributed to with pre tax dollars if I will be contributing with taxed money from my pay check?Stupid question? Probably, but I dont get it. Its not payroll deducted so where does it happen?  <response>: First, Im assuming you mean to open a traditional IRA through Vanguard. 401k accounts are only provided through your employer. Though if youre self-employed, you-as-employer can set up a 401k plan for you-as-employee.To your question: Yes, contributions during this year to the IRA are made using already-taxed money from your bank account. However, when you do your taxes next year, all your traditional IRA contributions are deducted from your taxable income, effectively become pre-tax contributions. Thatll reduce your taxes owed, and you basically get the taxes paid on that contributed money back as part of your refund. Just make sure you claim the contributions line 32 of the 1040 and youre set.Second point: IRA contributions are capped at 5500 per year total across all Roth Traditional IRAs. So if youre already maxing out your Roth IRA contributions, you cant make further contributions to a Traditional IRA. I wasnt sure if you were looking at switching your contributions from Roth - Traditional or looking into making additional savings. 