Solo 401(k) vs SEP-IRA: Which Is Better for Self-Employed

Quick Answer

A Solo 401(k) (also called a self-employed 401(k) or individual 401(k)) offers higher contribution limits and Roth options compared to a SEP-IRA. In 2026, a Solo 401(k) allows up to $69,000 in combined contributions (employee deferral + employer contribution), plus a $7,500 catch-up at age 50+. It also permits loans against your balance and offers Roth 401(k) option. However, Solo 401(k)s require more paperwork. For most solo entrepreneurs earning under $100,000, a SEP-IRA is simpler. For higher earners wanting Roth or loan features, a Solo 401(k) wins.

Solo 401(k) Contribution Limits in 2026

A Solo 401(k) has two components:

1. Employee deferral: You contribute up to $23,500 as the employee (or $31,000 if age 50+, including the $7,500 catch-up).

2. Employer contribution: You contribute up to 20% of your net self-employment income (after SE tax deduction), capped at a combined limit of $69,000 (employee + employer).

Example: You're a consultant with $120,000 net profit.

• Employee deferral: $23,500
• Employer contribution (20% of $120,000 × 92.35%): $22,164
• Total: $45,664

You've contributed $45,664, reducing your taxable income by $45,664. Compare to a SEP-IRA capping out at roughly $22,164 (the 20% calculation). The Solo 401(k) lets you contribute the additional $23,500 employee deferral.

Another example: You're age 52 earning $150,000 net profit.

• Employee deferral: $23,500
• Catch-up contribution (age 50+): $7,500
• Employer contribution (20% of $150,000 × 92.35%): $27,705
• Total: $58,705

The catch-up contribution and higher limits mean substantial tax savings.

Solo 401(k) vs. SEP-IRA Detailed Comparison

Why Choose a Solo 401(k)?

1. Roth Option: You can designate contributions as Roth 401(k), gaining tax-free growth. Important if you expect higher taxes in retirement.

2. Higher employee deferrals: The $23,500 employee deferral is in addition to employer contributions, not limited by income percentage.

3. Loans: Borrow up to 50% of your vested balance (up to $50,000 in 2026) for any purpose, with a 5-year repayment term. Useful for down payments, business expansion, or emergency cash.

4. Flexibility in low-income years: If your self-employment income is low, you can still contribute the $23,500 employee deferral (as long as you have earned income). With a SEP-IRA, low income means low contribution limits.

Example: You have a bad year, earning only $30,000 net profit.

• SEP-IRA contribution: $30,000 × 92.35% × 20% = $5,541
• Solo 401(k): $23,500 employee deferral (unchanged) + $5,541 employer contribution = $29,041

Even in a down year, the Solo 401(k) lets you shelter nearly $30,000, vs. only $5,541 with a SEP-IRA.

Why Choose a SEP-IRA?

1. Simplicity: Set up online in 10 minutes. Minimal paperwork annually.

2. Flexibility in timing: Contribute by your tax return deadline, even if extended (up to October 15). You can see your final net profit before committing.

3. No employee complications: If you ever hire an employee, you can discontinue the SEP without issues (just don't contribute that year for employees). Solo 401(k)s are only for the self-employed without employees.

4. Lower administration: No need to track loan activity, vesting, or complex regulatory compliance.

For a solo freelancer earning $60,000–$100,000 with no intentions of hiring employees, a SEP-IRA is fast and sufficient.

Setting Up a Solo 401(k)

1. Choose a provider: Fidelity, Schwab, E-Trade, or a retirement specialist.

2. Complete plan documents: You'll fill out a "plan adoption agreement" (usually a simple form provided by the provider).

3. Designate Roth or traditional (or both): Decide if you want all contributions as traditional (tax-deductible now, taxable in retirement) or Roth (no deduction now, tax-free in retirement), or split between both.

4. Set up payroll processing: If you're contributing as the "employer," you must treat it as payroll. This means calculating gross and net pay, withholding as needed (though self-employed typically don't have withholding), and filing payroll reports. This complexity is why many self-employed people find a Solo 401(k) burdensome.

5. Make contributions: Contribute by your tax deadline (April 15 for individuals with no extension, October 15 with extension).

6. File annual reports: If your plan balance exceeds $250,000 at year-end, file Form 5500-SF with the Department of Labor annually. Below $250,000, you only file Form 5500-SA with your tax return (much simpler).

Solo 401(k) Roth vs. Backdoor Roth

A Solo 401(k) with a Roth component is different from a backdoor Roth:

• Roth 401(k) contributions: You contribute after-tax money directly to a Roth 401(k) component. No income limits apply. You can contribute the full $23,500 employee deferral as Roth, plus employer contributions as Roth or traditional.

• Backdoor Roth: Contribute to a traditional IRA, then convert to a Roth IRA. Subject to pro-rata rules if you have other IRAs.

A Solo 401(k) with Roth is often simpler for high earners than managing backdoor Roths, especially if you have other IRA balances (which complicate backdoor Roths via pro-rata rules).

Example: You earn $200,000. You're ineligible for direct Roth IRA contributions (over phase-out limits). You can:

• Use a Roth 401(k) component: Contribute $23,500 as Roth, bypassing income limits.
• Or attempt a backdoor Roth: Contribute to traditional IRA, then convert, but pro-rata rules apply if you have other IRAs.

The Roth 401(k) is cleaner if available.

Loans From Your Solo 401(k)

Solo 401(k)s allow loans up to the lesser of:

• 50% of your vested balance, or
• $50,000 (2026 limit)

The loan must have a written promissory note and must be repaid within 5 years (or longer if used for a principal residence).

Example: Your Solo 401(k) has a $100,000 balance. You can borrow up to $50,000 (50% of balance, but capped at $50,000).

You'd repay the $50,000 over 5 years = $10,000/year (plus interest, typically prime rate + 1%, currently ~9%).

This is attractive for entrepreneurs needing cash for business expansion without triggering a taxable withdrawal (which would incur income tax + 10% penalty if under 59.5).

Income-Based Limits and Phase-Outs

Solo 401(k)s have no income-based contribution limits. Even if you earn $1,000,000+, you can contribute the same amounts as someone earning $100,000. This is different from backdoor Roths, which are only available when your income exceeds direct contribution limits.

For high-earning sole proprietors, a Solo 401(k) is the primary tax-deferred retirement saving vehicle (alongside maxing out the employee deferral, employer contribution, and catch-up if age 50+).

Employees and Solo 401(k)s

If you hire an employee, a traditional Solo 401(k) becomes complicated. The employee must be eligible for the same benefits as you. If you have employees, you typically need to:

• Offer matching contributions to eligible employees, or
• Discontinue the plan and switch to a SEP-IRA or other plan.

This is why Solo 401(k)s are "individual" plans—they're designed for solo self-employed people without employees.

Required Minimum Distributions (RMDs)

Starting at age 73 (2026 rules), you must take RMDs from your Solo 401(k) (traditional component). The RMD is calculated as your plan balance at the end of the prior year divided by your life expectancy factor (IRS tables).

Failure to take RMDs triggers a 25% penalty on the shortfall (reduced from 50% if caught and corrected timely).

You can delay RMDs if you're still working and own less than 5% of the business (rare for solo self-employed).

Choosing Between Them: A Decision Tree

Choose SEP-IRA if:

• You value simplicity and minimal paperwork.
• Your income is under $100,000.
• You don't need Roth or loan options.
• You might hire employees in the future (SEP is simpler to discontinue).

Choose Solo 401(k) if:

• You want a Roth option.
• You might need to borrow from your retirement savings.
• Your income exceeds $100,000 (higher limits are worth the complexity).
• You're age 50+ and want catch-up contributions.
• You want to contribute more than a SEP-IRA permits at your income level.

Sources

• Internal Revenue Service. "Solo 401(k) Plans." IRS.gov.
• Internal Revenue Service. Publication 560: Retirement Plans for Small Business.
• IRS Form 5500-SF: Short Form Annual Return/Report of Small Business Pension Plan.
• Department of Labor. "Solo 401(k) Compliance Guide." DOL.gov.
• CFA Institute. "Retirement Plans for the Self-Employed."