Max Your 2026 Retirement Limits: Solo 401k vs. SEP-IRA

Key Takeaways

• The 2026 Solo 401(k) total contribution limit is $70,000, allowing owners to stash more cash than standard employee plans.
• SEP-IRA limits for 2026 are capped at 25% of net adjusted self-employment income or $70,000, whichever is lower.
• Catch-up contributions for owners aged 50 and older remain a powerful lever, adding another $7,500 to your 401(k) deferrals.
• Solo 401(k) plans generally allow for higher contributions at lower income levels ($50k - $100k) compared to a SEP-IRA.

A husband-and-wife photography team in Georgia cleared $110,000 in net profit last year. They spent years using a standard Roth IRA, capped at just a few thousand dollars each, while watching their tax bill climb as their business grew. They hit a wall when they realized they were missing out on five-figure tax deductions simply because they hadn't opened a dedicated solo business retirement plan.

Retirement planning for a solo owner isn't about the gold watch; it's about high-level tax arbitrage. Every dollar you put into a pre-tax Solo 401(k) or SEP-IRA is a dollar the IRS doesn't tax at your highest marginal rate today. For 2026, the IRS has bumped these limits again, providing a larger shield for your hard-earned profits.

The 2026 Heavy Hitters: Solo 401(k) and SEP-IRA

Most solo owners choose between the Solo 401(k) and the Simplified Employee Pension (SEP) IRA. While they share the same $70,000 total cap for 2026 (up from previous years), the way you reach that cap is vastly different.

With a SEP-IRA, you're limited to roughly 25% of your net adjusted self-employment income. If you earn $60,000, you can only put away about $15,000.

A Solo 401(k) is significantly more flexible because you wear two hats: the employee and the employer. As the "employee," you can defer up to $23,500 (or $31,000 if you're 50+) regardless of the 25% rule. Then, the "employer" side of your business can contribute another 25% of your profit.

You can verify these official thresholds and catch-up rules via the IRS COLA increases page.

Contribution Math by Income Level

To see why the plan choice matters, look at how much you can actually contribute at different profit levels in 2026. These figures assume you're under age 50 and filing as a sole proprietor or single-member LLC.

Net Business Profit	SEP-IRA Max (Approx)	Solo 401(k) Max (Approx)
$50,000	$10,000	$33,500
$100,000	$20,000	$43,500
$200,000	$40,000	$63,500
$280,000+	$70,000	$70,000

At the $50,000 income mark, the Solo 401(k) is the clear winner for aggressive savers. You're able to shelter over 60% of your income from taxes. If you used a SEP-IRA at that same income level, you'd be stuck with a $10,000 contribution and a much higher tax bill.

The SIMPLE IRA: A Middle Ground for Teams

If you've a few employees, like a 4-person print shop in Ohio, the Solo 401(k) is off the table. Once you hire non-owner employees, you generally move into SIMPLE IRA or full 401(k) territory.

The 2026 SIMPLE IRA limit allows for $16,500 in salary deferrals. While lower than a Solo 401(k), it's much easier and cheaper to administer. Small businesses with 100 or fewer employees can check eligibility requirements and matching rules on the Department of Labor's retirement guide.

Decision Tree: Which Plan Hits Your Goals?

Choosing a plan depends on your cash flow and whether you plan to hire.

1. Do you want the absolute highest contribution at lower income levels? Pick the Solo 401(k). It requires a bit more paperwork (and an annual Form 5500-EZ once assets exceed $250,000), but the tax savings are hard to beat.
2. Is your income very high ($300k+) and do you want zero paperwork? The SEP-IRA is king. You can set it up at any brokerage in ten minutes and there are no annual IRS filings for the plan itself.
3. Do you've (or plan to have) employees? The SIMPLE IRA or a PEP (Pooled Employer Plan) are your best bets to stay compliant while still saving for yourself.

Deadlines and Execution

A 12-person HVAC shop in Texas recently learned the hard way that you can't always wait until tax day to set these up. While you can technically open and fund a SEP-IRA up until your tax filing deadline (including extensions), Solo 401(k) plans usually need to be established by December 31st to allow for employee salary deferrals during that tax year.

I recommend working with a CPA to run the numbers before December. You don't want to find out in April that you could have saved another $15,000 in taxes if you had just picked a different plan type. Open the account now, even if you only fund it with $100, to get the clock starting on any plan age requirements.

Open a Business Checking Account to Protect Your Assets to keep these retirement contributions clean and separate from your personal spending. Mixing funds is the fastest way to trigger an audit and lose the tax-deferred status of your hard-earned nesting egg.

Don't let your profit sit in a low-interest savings account where the IRS takes a 25% to 35% cut. Put it to work in a structure designed for owners, not employees.

---

📋 Disclaimer

This article is for informational purposes only and doesn't constitute legal, tax, financial, or professional advice. Laws and regulations change frequently, and the information presented may not reflect the most current legal developments. Always consult with a qualified professional (CPA, attorney, financial advisor) before making business decisions based on this content. MyBizNerd may receive compensation through affiliate links, but this never influences our recommendations.

---