My standard recommendation for a "start-up" is a 401(k) - for the very simple reason that you have considerably more choices in service providers (for now) than you do for 403(b) plans. I would add to that a few caveats - just for consideration. First, your choice of 401(k) plan providers for a "start-up" are much more limited - but depending on growth, that could change as more providers vie fo rthe business. Second, while I don't mean to pan insurance companies (I work for one), but many of the start-up 403(b) options are going to be group annuity products, and while they are light years better than contracts of years ago, the mere fact that it is an insurance contract adds some complexity (and maybe back-end misery, depending on the terms of that contract). To this day, I fight with co-workers who use "contract" and "plan" interchangeably - AND THEY ARE IN THE BUSINESS. Third and finally, there are still differences between k's and b's - and some like the special catch-up provisions in a b plan (but if they never had them, would they miss them in the future when it actually might be useful?)