Solo 401(k)s that allow after-tax contributions + megabackdoor roth


5+ Year Member
Jan 10, 2014
  1. Attending Physician
I want to max out $57,000 into a retirement account for 2020. I will have some 1099 income for the year, but not nearly enough to put away 20% from profit sharing and meet the maximum. Thus my plan is to max out on the employee portion + whatever I can get from profit sharing and meet the balance with an after-tax contribution and mega backdoor roth.

I've spent a couple of days trying to figure out which is the best brokerage that allows for everything I want in a prototype account. I even called TD Ameritrade but they don't seem to understand what after-tax contribution means, and in any case I don't think they allow it.

It leaves me to E-trade and Fidelity. Fidelity seems to allow after-tax contribution + mega backdoor but their employee portion does not offer a Roth 401k, My overall income will be low this year, therefore I prefer a Roth 401k instead of a Traditional.

The only other option seems to be E-trade, but I can't figure out by searching whether they allow it or not. I know they definitely do Roth 401k.

If E-trade doesn't work, I will go with Fidelity. In that case I am curious if the Fidelity prototype plan allow 401k to Roth rollovers while the plan is still active since they don't offer Roth 401k?

Any tips, suggestions, comments? Thanks for reading.
Last edited:


Senior Member
Moderator Emeritus
Gold Donor
10+ Year Member
Jun 12, 2006
  1. Attending Physician
Do you really think you'll be in a lower tax bracket now than retirement (Roth vs pre-tax question)? Either way, are you an employed physician with mostly W2 income? Fidelity is easy enough to set up for a solo 401k. I did most of the work but decided not to go through with it in the end since my wife's 1099 income was so low the year I was going to create the account.

By the way you may want to ask the same question on the WCI Facebook page or forum.

The White Coat Investor

Practicing Doc and Blogger
Partner Organization
15+ Year Member
Nov 18, 2002
  1. Attending Physician
You'll need a customized solo 401(k) to get that option. It'll cost you a few hundred dollars a year. You can't get it from a cookie-cutter Vanguard, Fidelity, eTrade, TD Ameritrade, or Schwab solo 401(k). It's generally the same folks who offer a self-directed feature in their i401(k)s.

The only people I know who do it have a financial conflict of interest with me (i.e. they advertise with me). But not telling you who they are seems to be a greater disservice, so I'll just disclose the conflict and let you do what you want with the information. Here's the list:

I'm sure they have competitors, but these are the folks I know.

Your message may be considered spam for the following reasons:

  1. Your new thread title is very short, and likely is unhelpful.
  2. Your reply is very short and likely does not add anything to the thread.
  3. Your reply is very long and likely does not add anything to the thread.
  4. It is very likely that it does not need any further discussion and thus bumping it serves no purpose.
  5. Your message is mostly quotes or spoilers.
  6. Your reply has occurred very quickly after a previous reply and likely does not add anything to the thread.
  7. This thread is locked.
About the Ads