It may be an issue of not understanding what that is. Some of the questions that would lead you to this answer are 1) Do they allow in process roll over of any kinda of investments? (My company does not allow in process roll overs for any tax advantaged account, but did allow 2 in process roll overs per year for after tax non-Roth investments. Even some of the 401k company's employers didn't understand this.) 2. What is the limit for invested money in the 401k? [The yearly limit for 2017 is $54,000 for company match, your tax advantaged contribution, and your non advantaged (mega back door) portion. If you make $100k and are limited by your company to invest up to 18%, then this would all be your 401k or Roth 401k investment. Anything above this could be your MBDR investment. My company limited us to 40%, so if I made $100k, I could put $18k in TA, then $22k in MBDR, plus the match, as long as this is under that yearly $54k limit.