1099 S-corp PLLC looking at Solo 401k + MBDR?
Here's my situation. I am a pure 1099 (no W2 income) under the age of 50 and have a PLLC that I recently changed to S-corp this year. For tax purposes I am in Nevada (no state income tax). My wife is a W2 earning ~100k/yr. I earn ~90k/month (~$1mil/yr) as a 1099. With the start of being a S-corp I am doing payroll via Gusto and paying myself $200k/yr.
I am trying to maximize my tax strategy, and my colleagues keep mentioning that I should look into a Solo 401k and potentially "mega back door roth" (MBDR). I already have a small Roth IRA from my early days before hitting the income limit with Fidelity.
It is my understanding that I cannot open up a Solo 401k directly with Fidelity and convert it into my existing Roth and that I would need a 3rd party. There doesn't seem to be many options out there and the only option I keep seeing mentioned is "mysolo401k".
Their website seems antiquated (I think this has been beaten to do death) but their fees seem reasonable. Am I correct in thinking this is the best option to allow MBDR? I still don't understand why I need this 3rd party to open up another fidelity account. And will it allow me to rollover into my existing Roth IRA?
For 2026, maximum contribution limit is $72k with a max employee contribution of $24.5k that I plan to make. This would leave the "business" or employer/PLLC contribution at $47.5k.
Is my math checking out correctly? My CPA hasn't been much help and keeps pushing this CFP on me. My colleagues have very mixed responses and generally say a CFP isn't worth their expense. I believe I will have to file form 5500EZ or face a large penalty.
- Would my CPA be able to do the 5500EZ form with my combination of Gusto/mysolo401k/Fidelity?
- Is form 5500EZ something that I need to do?
- Is there a better combination?
- Is my math flawed or do I need to change something?
- Am I missing anything?