Favor contributing to Roth 401(k) when in relatively low tax bracket and favor contributing to traditional 401(k) when in relatively high tax bracket. Current Federal Tax Brackets: 10% 12% 22% 24% 32% 35% 37%. If in 10% or 12% FTB Roth 401(k) is good default choice. You may not know what future tax bracket will be at retirement but you likely have fair idea what your foreseeable working tax brackets will be depending on your career.
