How to Guide-Mega Back Door Roth Solo 401k Conversion of Fidelity Non-Prototype Solo 401k Brokerage Account to Roth IRA at Vanguard

My Solo 401k Financial clients also have the option to convert their voluntary after-tax solo 401k funds held in a non-prototype brokerage account at Fidelity Investments to their Vanguard Roth IRA. The following video and procedure detail the following:

  • How to open a mega backdoor Roth solo 401k with My Solo 401k Financial;
  • How open the solo 401k non-prototype brokerage accounts at Fidelity Investments;
  • How to convert the voluntary after-tax solo 401k funds from Fidelity Investments to the Roth IRA at Vanguard; and
  • How to report the non-taxable conversion of voluntary after-tax solo 401k funds to the Vanguard Roth IRA.
  • Video Slides: Mega Backdoor Fidelity Roth Solo 401k to Roth IRA at Vanguard


Conversions are reported in the year that the funds are actually moved over to the Roth account. 

The solo 401k contribution rules are different from the  conversion rules. Contributions can be made by your business tax return due date plus any timely filed extension for the prior year.

In sum, the voluntary after-tax solo 401k conversion will be nontaxable regardless if  you convert the after-tax contributions that were made in 2021 or in 2022 for 2021.

About Mark Nolan

Each day I speak with energetic entrepreneurs looking to take the plunge into a new venture and small business owners eager to take control of their retirement savings. I am passionate about helping others find their financial independence. Having worked for over 20 years with some of the top retirement account custodian and insurance companies I have a deep and extensive knowledge of the complexities of self-directed 401ks and IRAs as well as retirement plan regulations. Learn more about Mark Nolan and My Solo 401k Financial >>


  • Popular Video

  • ROBS 401k Funding Process

  • Solo 401k Contributions Including Mega

  • Checkbook IRA LLC

  • About MySolo401k

    We help our clients take control of their retirement money. Our products and services provide our clients the freedom to invest their retirement savings in their own business as well as alternative investments such as real estate, private companies, promissory notes, precious metals, tax liens and equities.
    Learn more

    Connect with us

  • We’re here to help.

    Call: 800-489-7571


    8:00 am - 4:00 pm PT

    Why us?