Compare Investment Strategies: Taxable vs Roth IRA vs Mega Backdoor Roth Solo 401k

When you have money to invest, where you put it matters just as much as how much you invest. In this session, the team at My Solo 401k Financial compares three core strategies side by side: a taxable brokerage account, a Roth IRA, and the Mega Backdoor Roth Solo 401k. Each one has very different contribution limits, tax treatment, withdrawal rules, and loan access — and understanding those differences can help self-employed savers make a more confident decision in 2026.

This article is provided for educational purposes only and should not be construed as tax, legal, or investment advice. Always consult your own tax attorney and financial professional before making an investment decision.

Watch: A side-by-side breakdown of taxable, Roth IRA, and Mega Backdoor Roth Solo 401k investing strategies for 2026

2026: The New Rules of the Game — Higher Limits

The 2026 tax year brings higher contribution limits across the board. For a Solo 401k, the employee contribution limit increased to $24,500, with more available if you are age 50 or older, and the overall limit rose to $72,000. For IRAs, the limit increased to $7,500, or $8,600 if you are age 50 or older.

Super Catch-Up Contributions

Super catch-up contributions apply to 401k plans that support them, such as the plan offered by My Solo 401k Financial. Historically, savers age 50 and older have always been able to make catch-up contributions, and they still can — the catch-up contribution limit is now $8,000, assuming you have the self-employment income to justify it. But now, if you are age 60 to 63 as of the end of 2026, thanks to the SECURE Act 2.0, you may be able to contribute $11,250 instead of $8,000 — the so-called super catch-up contribution.

The Roth Mandate for High Earners

⚠ Important: Beginning in 2026, there is a Roth mandate for high earners. If your W-2 wages are over $150,000 and you are of an age where you are making catch-up contributions (age 50 or older), any catch-up contributions you want to make must be made on a Roth basis starting in 2026.

Solo 401k Eligibility: Laying the Foundation

Before comparing strategies, it helps to confirm who qualifies for a Solo 401k. There are two halves to the eligibility equation:

✔ Example — Who Qualifies:

Self-employment income: You must generate earned self-employment income — whether through 1099 work or a business such as a sole proprietorship, LLC, or S-corp. Sole proprietors report income on Schedule C of the 1040; S-corp or C-corp owners use W-2 wages; partnerships report on Line 14 of the K-1 from a Form 1065.
No full-time employees: There can be no non-owner, non-spouse full-time W-2 employees. You and your spouse can both work in the business, and you can use contractors paid on a 1099 basis — you just cannot have non-owner, non-spouse full-time W-2 employees.

Strategy 1: The Taxable Brokerage Account

The first strategy is investing through a taxable brokerage account — a non-retirement account you open, for example, in your own name using your savings. Its defining features:

Feature	What It Means
No contribution limits	There are no annual contribution caps — you can invest as much as you want.
Tax-loss harvesting	Losses on specific investments may offset other income. Work with your tax advisor to consider this.
Full liquidity	No withdrawal penalty and no triggering event required to access the funds — it is simply an account in your name.
Tax drag	When you realize gains — dividends or selling investments — you owe taxes (short-term or long-term capital gains). That reduces the principal left to grow.

ℹ Info Highlight — What is “Tax Drag”?
Tax drag refers to the taxes you pay along the way in a taxable brokerage account. As you realize gains, you hand some of that money to Uncle Sam — leaving you with less principal to grow going forward. Retirement accounts like a Roth IRA or Roth Solo 401k avoid this because growth is always at least tax-deferred.

Strategy 2: The Roth IRA

Anybody can set up a Roth IRA — but whether you can contribute depends on your situation. You need earned income to justify a contribution, and you cannot make too much money: high earners are not able to make a direct Roth IRA contribution. If you are eligible and structure it properly with your tax advisor, you may be able to make a backdoor Roth IRA contribution — first making a non-deductible contribution to an IRA, then transferring it to a Roth IRA.

The Tax Advantage: No Tax Drag

Unlike a taxable account, a Roth IRA offers the potential for totally tax-free growth. Gains — dividends or realized gains from selling assets — are tax-deferred, and ultimately may be tax-free if you satisfy the qualified Roth IRA distribution rules. Even if you do not ultimately satisfy those rules, while the money is in the account it is at least tax-deferred. That means no tax drag: dividends and principal can keep compounding without losing ground to taxes each year.

Accessing the Money: Ordering Rules

Withdrawals from a Roth IRA follow ordering rules: you first take out your contributions (your basis), then conversions (money converted from another retirement account), and finally the gains. Whether the gains come out tax-free depends on whether it is a qualified Roth IRA distribution. One advantage many savers value: you can access your basis — your original contributions — at any time, tax-free and penalty-free, because you already paid taxes on that money when you contributed it on an after-tax basis.

Strategy 3: The Roth Solo 401k

The Roth Solo 401k works much like a Roth IRA — the key difference is that you can contribute far more. Where the most a 50-plus saver can put in a Roth IRA is $8,600 for 2026, a self-employed individual can contribute 100% of self-employment income up to $24,500 to a Roth Solo 401k. If you are age 60 to 63 as of the end of 2026 and have the income to justify it, you could contribute up to $35,750 (or $8,000 if 50+) — the standard $24,500 Roth employee contribution bucket plus an additional $11,250 super catch-up contribution (or $8,000 if 50+).

⚠ Important — Employee Limits Apply at the Employee Level: If you have a W-2 day job and already max out your employee contributions to your day-job 401k, you cannot make additional Roth employee contributions to your Solo 401k. However, you can still make voluntary after-tax contributions — so the Mega Backdoor Roth strategy remains available to you.

No Tax Drag, But Restrictive Access

Just like a Roth IRA, the Roth Solo 401k has no tax drag — all gains are tax-deferred and possibly tax-free, depending on whether you make a qualified distribution. On the surface, access is more restrictive: unlike a Roth IRA, you cannot skim contributions at any time. Roth Solo 401k funds are locked until you meet a triggering event — mainly terminating the plan or turning age 59½. That restriction can keep you disciplined, since more money stays invested and growing.

ℹ Info Highlight — The Solo 401k Loan Bridge:
There is an exception to the restrictive access: Solo 401k loans. With a plan like the one offered by My Solo 401k Financial, you can borrow up to 50% of your total balance, not to exceed $50,000. The loan is repaid in equal monthly or quarterly payments of principal and interest (prime plus 1%, or a CD rate plus 2%) — and the interest is paid back to your own retirement account. My Solo 401k Financial prepares the loan documents at no additional charge.

Strategy 4: The Mega Backdoor Roth Solo 401k

For many high-income business owners, the Mega Backdoor Roth Solo 401k is the ultimate strategy for getting the most dollars into a Roth account. For 2026, individuals can shelter up to $72,000 — or even more if they are age 50 or older — with those funds ending up in a Roth account. You can learn more in our detailed guide on the Mega Backdoor Roth using a Solo 401k plan.

How It Works: A Two-Step Strategy

Step	Action
Step 1	Make a voluntary after-tax Solo 401k contribution. The My Solo 401k Financial plan allows for this.
Step 2	Convert those funds to a Roth account, where they gain the potential for tax-free growth like any other Roth dollars.

Your Two Conversion Options

Once you have made your voluntary after-tax contribution, you have a choice about where the converted funds land:

Consideration	Option A: In-Plan Conversion (Roth Solo 401k)	Option B: Transfer to Roth IRA
Where the money stays	Keeps the money inside the Solo 401k.	Moves the money out of the Solo 401k into a Roth IRA.
Loan access	You can take a Solo 401k loan.	You lose the ability to take a loan — loans are not available from any IRA.
Alternative investments	Can invest in alternatives such as crypto and real estate within the plan.	Harder — you would need a specialty Roth IRA, plus an LLC underneath it for checkbook control.
Early access	Locked until you meet a triggering event, like any other Roth Solo 401k dollars.	Treated as a conversion — after five years, follows Roth IRA ordering rules, giving somewhat earlier access.

✔ Example — A Helpful Exception: Voluntary after-tax Solo 401k funds are one of the exceptions to the triggering-event rules. They can be transferred out of the Solo 401k at any time — without being 59½, terminating the plan, or otherwise meeting a triggering event. That is what makes Option B possible.

Side-by-Side Comparison

Here is a high-level look at how all four approaches stack up for 2026:

Feature	Taxable Account	Roth IRA	Roth Solo 401k	Mega Backdoor Roth Solo 401k
2026 Limit	No limit — save as much as you want.	$7,500, or $8,600 if age 50+.	$24,500, plus $8,000 (age 50+) or $11,250 (age 60–63).	Up to $72,000 of self-employment income; can be transferred out to a Roth IRA.
Tax Drag	Yes — the only account where it applies.	None — always tax-deferred.	None — always tax-deferred.	None — always tax-deferred.
Withdrawals	Taxable, available anytime.	Contributions accessible first, anytime — tax-free, penalty-free.	Restrictive — must meet a triggering event.	If transferred to a Roth IRA, follows Roth IRA ordering rules (after 5 years).
Loan Option	Not needed — full access anytime.	Not available from any IRA.	Yes — up to 50% of the balance, not to exceed $50,000.	Option A (Roth Solo 401k): loan available. Option B (Roth IRA): no loan.

Questions From the Webinar

Can I make my annual Roth contribution directly into my existing Roth Solo 401k account?

Yes. A webinar attendee noted that they already have a Roth Solo 401k with My Solo 401k Financial and had previously contributed through an in-plan conversion of pre-tax Solo 401k funds. Our plan does allow for those in-plan conversions — they are taxable, since you are moving from pre-tax to Roth status, and they are reportable, so customers provide the information needed to prepare the 1099-R (this can be done at mysolo401k.net/forms).

The same Roth account can be used for both conversions and contributions — whether a pre-tax-to-Roth conversion or an after-tax-to-Roth conversion. You do not need to open a separate Roth account to make yearly Roth Solo 401k contributions.

⚠ Important Clarification: A Solo 401k is not a Roth IRA. If you want to make a Roth IRA contribution, you cannot do it through your Solo 401k account — you would make it to an actual IRA account, such as a Roth IRA at a brokerage. As always, check with your tax advisor to confirm you are eligible and have the income to support a Roth IRA contribution.

Ready to Maximize Your Roth Savings With a Mega Backdoor Roth Solo 401k?

Whether you want to keep funds in your plan for loans and alternative investments or transfer them to a Roth IRA, the team at My Solo 401k Financial can help you set up the right Solo 401k structure for your goals.

Next Steps: Get Started Today!

Remember: This information is provided for educational purposes only. Always consult with qualified tax, legal, and investment professionals before making investment decisions with your retirement funds.