Another thing to keep an eye on when making this decision is fees. A lot of 401ks have terrible fees that will eat your growth. Whereas if you use a Vanguard IR

Another thing to keep an eye on when making this decision is fees. A lot of 401ks have terrible fees that will eat your growth. Whereas if you use a Vanguard IRA you can easily get into funds with 0.18% fees or less. I've used a non-matching 401k mostly to save more money (and roll it into a Vanguard IRA as soon as possible) but a lot of advice I've read on the internet suggests maxing a Roth IRA before contributing to a non-matching 401k. (I don't have a Roth yet because it's always seemed crazy to me that my taxes will be higher in retirement than now. I see in this thread they have other advantages, like being able to withdraw principle.)