How to Upgrade a Human Interest Solo 401(k) to Allow 2025 Mega Backdoor Roth Contributions
Published by My Solo 401k Financial | Educational Content | Solo 401(k) Planning
Watch: My Solo 401k Financial walks you through upgrading a Human Interest Solo 401(k) to unlock Mega Backdoor Roth contributions for 2025
Who Does This Apply To?
If you currently hold a Solo 401(k) plan at Human Interest — or at another major provider such as Fidelity, Schwab, or Vanguard — this guide explains exactly how you can upgrade that plan to one that supports Mega Backdoor Roth Solo 401(k) contributions for the 2025 plan year.
The core issue is straightforward: Human Interest’s Solo 401(k) plan documents do not permit Mega Backdoor Roth contributions. That is a plan-document limitation — not an IRS rule. By restating your plan under IRS-approved documents that do allow it (such as those provided by My Solo 401k Financial), you can unlock this powerful strategy and several other advanced features.
Solo 401(k) Eligibility Requirements
Before upgrading, confirm that you meet the basic Solo 401(k) eligibility requirements. You must be self-employed and your business must be an owner-only operation — meaning you have no non-owner, non-spouse full-time W-2 employees.
Eligible Business Structures
You can operate your business as any of the following and still qualify for a Solo 401(k):
a sole proprietor,
a single-member LLC,
an S corporation,
a C corporation,
or even a partnership — as long as you are reporting earned self-employment income and the business meets the owner-only test.
Why Upgrade? Limitations of Basic Solo 401(k) Plans
Basic Solo 401(k) plans offered by Human Interest, Fidelity, Schwab, and similar providers lack the plan-document provisions required for advanced strategies. The table below compares what you get with a basic provider plan versus a fully upgraded My Solo 401k Financial plan.
Understanding the Restatement Process
The upgrade process is formally called a restatement. It is important to understand that this is not the same as shutting down your existing Solo 401(k) and opening a brand-new plan. Your plan continues to exist — the difference is that it will now be governed by new, IRS-approved plan documents. Those documents are the key to unlocking advanced features like the Mega Backdoor Roth.
💡 Example: What a Restatement Looks Like
Think of it as a “cut and paste” for your plan documents. You remove the Human Interest plan documents from your existing Solo 401(k) and replace them with IRS-approved documents from My Solo 401k Financial. Your plan history, contribution records, and tax treatment all carry forward — but now your plan supports Mega Backdoor Roth contributions, loans, and alternative investments.
New Accounts Are Required
Because Human Interest will not open accounts for customers who bring their own third-party plan documents, you will need to open new custodial accounts at a brokerage of your choice. My Solo 401k Financial is custodian-neutral and has helped customers open accounts at hundreds of different banks, credit unions, and brokerages. The two most popular options are Fidelity and Schwab, but you are not limited to these.
My Solo 401k Financial will guide you through opening these new accounts and will then help you transfer your existing Human Interest balances over. That transfer is not taxable and not reportable — it is simply a movement of funds from one Solo 401(k) account to another account under the same restated plan.
How the Mega Backdoor Roth Solo 401(k) Strategy Works
The Mega Backdoor Roth is a two-step process that allows you to contribute significantly more to a Roth account than the standard Roth IRA or Roth 401(k) contribution limits would otherwise permit.
ℹ️ 2025 Contribution Limits at a Glance
For 2025, the total Solo 401(k) contribution limit (employee deferrals + employer contributions + voluntary after-tax) is $70,000 — or $77,500 if you are age 50 or older. The voluntary after-tax contribution room available through the Mega Backdoor Roth can be roughly ten times larger than a standard Roth IRA contribution limit and multiple times larger than the standard Roth 401(k) deferral limit.
Step 1: Make a Voluntary After-Tax Contribution
You first contribute after-tax dollars into a dedicated voluntary after-tax Solo 401(k) sub-account. This step is what gives you access to the higher overall contribution limits. These funds are deposited on an after-tax basis — meaning you do not receive a tax deduction for them at this stage.
Step 2: Convert to a Roth Account
You then move those after-tax funds into either a Roth Solo 401(k) sub-account (an in-plan conversion) or transfer them to a Roth IRA. Once inside a Roth account, all future investment gains enjoy tax-free growth potential. This second step is reportable on a 1099-R, which My Solo 401k Financial will prepare for you at no additional charge.
SECURE Act Tax Credits: Up to $1,500
One of the additional benefits of upgrading your Solo 401(k) is eligibility for SECURE Act tax credits. These credits are not limited to brand-new plans — even existing plans that are upgraded (restated) to include the required features qualify. My Solo 401k Financial automatically drafts plan documents to satisfy these requirements.
ℹ️ SECURE ACT Tax Credit Breakdown
Eligible businesses can claim up to $1,500 in total tax credits — structured as $500 per year for three consecutive years. This applies to both new Solo 401(k) plans and to existing plans that have been restated to meet the qualifying criteria.
Solo 401(k) Loans: Borrow From Your Own Plan
Another major advantage of upgrading is access to Solo 401(k) loans. With a restated plan from My Solo 401k Financial, you can withdraw funds from your Solo 401(k) and use them for any purpose — business or personal — without triggering taxes or penalties, as long as the withdrawal is properly documented as a loan.
Investment Freedom: Beyond Traditional Brokerage
A restated Solo 401(k) with My Solo 401k Financial also opens the door to alternative investments — an area where basic provider plans fall short. In addition to traditional brokerage investments (stocks, bonds, mutual funds, and ETFs), customers of My Solo 401k Financial are able to invest in true alternative asset classes.
💡 Popular Alternative Investments in a Solo 401(k)
Customers of My Solo 401k Financial have used their Solo 401(k) to invest in real estate, private equity, precious metals, and cryptocurrency (crypto), among other asset classes. This level of investment freedom is simply not available with basic provider plans like Human Interest.
Ongoing Compliance Support
My Solo 401k Financial provides comprehensive ongoing compliance support for your Solo 401(k). What is needed will depend on the specifics of your plan, but all customers receive certain baseline services automatically.
What’s Included
Mandatory plan updates and amendments are handled proactively — My Solo 401k Financial will reach out when updates or amendments are needed, so you never miss a deadline. If you take a Solo 401(k) loan, loan documents are prepared within one business day at no additional cost. If you make a Mega Backdoor Roth conversion, the required 1099-R tax form is prepared and filed for you — again, at no additional charge — as long as you submit the required information in a timely manner.
Form 5500-EZ Filing
If the value of your Solo 401(k) plan exceeds $250,000 (including the value of any defined benefit plan), an informational filing return called the Form 5500-EZ is required. Customers simply need to notify My Solo 401k Financial once the plan value crosses that threshold. We will then guide clients through the 5500-EZ filing process including preparing the 5500-EZ for clients in the IRS electronic filing system (EFAST) — no hassle for the account holder.
Is There Still Time for 2025?
Yes — if you already have an existing Solo 401(k) (whether at Human Interest or elsewhere), there is still time to upgrade and make 2025 Mega Backdoor Roth Solo 401(k) contributions. However, it is strongly recommended that you act sooner rather than later to give yourself adequate time to determine contribution amounts and complete the restatement process.
⚠️ Important: Act Promptly
While there is still time to make 2025 Mega Backdoor Roth contributions, delays reduce your window. My Solo 401k Financial offers a quick one-minute application, and restatement documents are prepared within the same business day once the application and payment are submitted. The sooner you start, the more flexibility you have in planning your contributions.
Ready to Upgrade Your Solo 401(k) and Unlock the Mega Backdoor Roth?
Whether you currently have a Human Interest Solo 401(k) or a plan at another provider, My Solo 401k Financial can help you restate your plan and access advanced features — including Mega Backdoor Roth contributions, Solo 401(k) loans, alternative investments, and SECURE ACT tax credits.
Next Steps:
⚠️ Important Disclaimer
This presentation is provided for educational purposes only and should not be construed as tax, legal, or investment advice, nor as a solicitation. When making an investment decision, please consult with your tax attorney and financial professional.
