Merrill Edge SEP IRA vs. Solo 401k: The 2026 Showdown

Watch: A 2026 head-to-head comparison of the Merrill Edge SEP IRA and the Solo 401k from My Solo 401k Financial.

Self-employed individuals weighing retirement plan options at Merrill Edge often start with the same question: SEP IRA or Solo 401k? On the surface, both plans share the same overall contribution ceiling for 2026 — $72,000. But the path to that ceiling looks completely different, and for most solopreneurs, those differences create a massive gap in actual savings potential. This guide breaks down the 2026 numbers, the contribution mechanics, the Mega Backdoor Roth opportunity, and why the structure you choose can dramatically change your retirement outcome.

The $72,000 Question: Same Ceiling, Different Paths

For 2026, the overall annual additions limit is $72,000. Both the Merrill Edge SEP IRA and the Solo 401k share this same overall ceiling. The catch? How you actually fill that bucket — and how much business income you need to do it — varies enormously between the two plans. And for participants age 50+, the Solo 401k can actually go even higher thanks to catch-up contributions.

Info Highlight: The $72,000 overall limit is shared across plans. If you contribute to both a SEP IRA and a Solo 401k, the employer contributions are aggregated — you cannot double-fill the bucket.

How SEP IRA Contributions Work

A SEP IRA only accepts employer contributions — there is no employee contribution option. Because of that, contributions are always limited to a percentage of your compensation:

S corporation or C corporation: Up to 25% of your W-2 wages from the business.
Sole proprietorship: Up to 20% of your self-employment compensation (line 31 of Schedule C, less one-half of self-employment tax).
Partnership: Up to 20% of your self-employment compensation (line 14 of your K-1, less one-half of self-employment tax).

The bottom line: you need a lot of income to fully fund a SEP IRA. A sole proprietor would need over $360,000 of business income to justify the full $72,000 contribution.

⚠ Important: Because SEP IRA contributions are strictly percentage-based, lower-income solopreneurs hit a hard ceiling far below $72,000 — even if they want to save more. This is the single biggest reason a SEP IRA underperforms for most self-employed savers.

How Solo 401k Contributions Work

The Solo 401k uses multiple buckets to reach the same overall limit, which dramatically lowers the income required:

Bucket 1 — Employee Contributions: Up to $24,500 for 2026 (dollar-for-dollar, 100% of self-employment compensation), plus catch-up contributions if age 50+.
Bucket 2 — Employer Contributions: Same percentage rules as the SEP IRA (20% sole prop / partnership; 25% S-corp / C-corp).
Bucket 3 — Voluntary After-Tax Contributions: Up to 100% of self-employment compensation (subject to the overall limit). This is the third type of contribution that powers the Mega Backdoor Roth strategy — and it is only available with a plan that allows for it, like the one offered by My Solo 401k Financial.

✓ Example — Joseph’s Question: A solopreneur with a day job 401(k) maxes out the day job at $24,500. Because the day job and the self-employed business are unrelated, the section 415(c) annual additions limit is not shared. The solopreneur could contribute an additional $72,000 as a voluntary after-tax Solo 401k contribution — for a combined $96,500 across both plans. (Note: this exception does not apply if the day job plan is a 403(b).)

2026 Contribution Mechanics: Side-by-Side

Contribution Type	Merrill Edge SEP IRA	Solo 401k (My Solo 401k Financial)
Employee Contribution	❌ Not Allowed	✅ Up to $24,500 (2026)
Employer Contribution	20% (sole prop) / 25% (S-corp)	20% (sole prop) / 25% (S-corp)
Voluntary After-Tax (Mega Backdoor Roth)	❌ Not Allowed	✅ Up to $72,000 overall limit
Roth Employee Contributions	❌ Not Allowed	✅ Available
Catch-Up (Age 50+)	❌ Not Allowed	✅ Available
Income Required to Hit $72,000 (Sole Prop)	~$360,000+	Significantly less

The Mega Backdoor Roth: A Solo 401k–Only Strategy

The Mega Backdoor Roth is one of the most powerful strategies for high-earning solopreneurs to build a tax-free nest egg — and it is simply not available with a SEP IRA. Here’s why: the strategy requires voluntary after-tax contributions, which are a third type of contribution that the SEP IRA does not accept.

How the Mega Backdoor Roth Works in Two Steps

Step 1 — Voluntary After-Tax Contribution: Contribute up to 100% of your self-employment compensation (dollar-for-dollar, up to the $72,000 overall limit for 2026) to the after-tax bucket of your Solo 401k.
Step 2 — In-Plan Roth Conversion: Immediately convert those after-tax funds to your Roth Solo 401k account (or out of the plan to a Roth IRA), where they will benefit from tax-free growth — just like a Roth IRA.

For a deeper dive into the strategy, see our full guide on the Mega Backdoor Roth using a Solo 401k plan.

Info Highlight: The voluntary after-tax contribution limit is not reduced by employee contributions made to a separate day-job 401(k). This is another example of what makes the strategy so powerful for solopreneurs with W-2 day-job income.

SECURE Act Tax Credits: Up to $1,500 in Free Money

Setting up a Solo 401k through My Solo 401k Financial enables solopreneurs to claim tax credits under the SECURE Act — specifically $500 per year for the first three years. These credits are available for both new plans and existing plans that are upgraded to our Solo 401k.

✓ Example — Plan Effectively Free for 7 Years: Initial cost is $650 ($525 establishment fee + first $125 annual fee). The annual fee is then $125 per year thereafter. The $1,500 in SECURE Act tax credits more than covers our fees for the first seven years.

Auto-Enrollment Requirement

To claim the credit, the plan must include an auto-enrollment feature, which is automatically built into our plan documents. The feature carries a default 3% contribution rate — but as the solopreneur and the only participant, you have the right to opt out of that default and contribute on whatever schedule and amount you prefer (subject to the limits and deadlines).

⚠ Heads Up: SECURE Act tax credits are not available with a SEP IRA, including a Merrill Edge SEP IRA. They are only available when you set up a Solo 401k with the right plan documents.

Alternative Investments: Real Estate, Crypto, and Beyond

One of the standout advantages of bringing your own Solo 401k plan documents to Merrill Edge is access to alternative investments: real estate, crypto, private placements, and private stock. Merrill Edge does not charge to open accounts for a third-party plan when you bring your own plan documents.

The UDFI Tax Exemption for Real Estate

For real estate investors using retirement funds combined with non-recourse financing, there is a unique tax advantage. Normally, debt-financed income flowing back to a self-directed IRA triggers Unrelated Debt-Financed Income (UDFI) tax. However, the Solo 401k has a special exemption: if the debt-financed real estate is held inside a Solo 401k, the UDFI tax does not apply. This exemption is not available to a SEP IRA.

Info Highlight on Non-Recourse Financing: Specialty lenders that lend to retirement accounts typically require around 50% down. The account holder cannot personally guarantee the loan — the lender’s only recourse is the underlying property as collateral.

Head-to-Head: Merrill Edge SEP IRA vs. Solo 401k

Feature	Merrill Edge SEP IRA	Solo 401k (My Solo 401k Financial)
2026 Max Contribution	$72,000 (requires $360k+ income)	$72,000 (with much less income)
Mega Backdoor Roth	❌ Not Allowed	✅ Full Roth options
Participant Loans	❌ Loans not allowed from any IRA	✅ Loan documents prepared (no extra charge)
Catch-Up Contributions (50+)	❌ Not Allowed	✅ Available
SECURE Act Tax Credits	❌ Not Available	✅ Up to $1,500 over 3 years
Real Estate / Crypto / Private Placements	❌ Not Available	✅ Allowed by plan documents
UDFI Exemption (Debt-Financed Real Estate)	❌ Not Available	✅ Available

The Bottom Line for 2026

On paper, the Merrill Edge SEP IRA and the Solo 401k share the same $72,000 ceiling. In practice, they are not remotely the same product. The Solo 401k from My Solo 401k Financial gives solopreneurs multiple contribution buckets, the Mega Backdoor Roth strategy, catch-up contributions, participant loans, SECURE Act tax credits, and access to alternative investments like real estate and crypto with a UDFI exemption — none of which the SEP IRA offers. For most self-employed savers in 2026, that combination of features makes the choice clear.

Ready to Maximize Your 2026 Retirement Savings at Merrill Edge?

Whether you are starting fresh or upgrading from a SEP IRA, we can help you set up the right Solo 401k structure to unlock the Mega Backdoor Roth, catch-up contributions, and SECURE Act tax credits.

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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.