Solo 401(k) vs SEP IRA: Which Is Better for Freelancers?

When you're self-employed, no one's matching your 401(k) — you're on your own to build retirement savings. The two most popular retirement plans for freelancers are the Solo 401(k) and the SEP IRA. Both offer serious tax advantages and high contribution limits, but they work differently. This guide compares them side-by-side so you can pick the one that fits your business in 2026.

Key Takeaways

• Solo 401(k) lets you contribute more at lower income levels because you can make both employee and employer contributions, plus a $23,500 employee deferral for 2026.
• SEP IRA is simpler to administer — less paperwork, easier to open, and no annual filing requirements unless you have employees.
• Solo 401(k)s offer Roth options and loan features that SEP IRAs don't, giving you more flexibility.
• If you have full-time W-2 employees (other than your spouse), a SEP IRA may be required — Solo 401(k)s are only for businesses with no employees or just the owner and spouse.
• Both plans let you deduct contributions from your taxable income, reducing your self-employment tax burden.

What Is a Solo 401(k)?

A Solo 401(k) — also called an Individual 401(k) or one-participant 401(k) — is a retirement plan designed for self-employed individuals with no employees (except a spouse). It works just like a corporate 401(k), but you're both the employer and the employee.

How Solo 401(k) Contributions Work

You can contribute in two ways:

• Employee deferrals: Up to $23,500 in 2026 ($31,000 if you're 50 or older). This comes from your net self-employment income and can be traditional (pre-tax) or Roth (after-tax).
• Employer profit-sharing: Up to 25% of your net self-employment earnings (after deducting half of your self-employment tax and your employee deferrals).

The total combined limit is $70,000 for 2026 ($77,500 if 50+).

Key Features

• Roth option available: You can designate some or all of your employee deferrals as Roth contributions.
• Loan option: Borrow up to $50,000 or 50% of your account balance.
• No W-2 employees allowed: If you hire full-time employees (other than your spouse), you can't use a Solo 401(k) anymore — you'd need to switch to a different plan.
• Annual filing required if balance exceeds $250,000: You'll need to file Form 5500-EZ.

What Is a SEP IRA?

A SEP IRA (Simplified Employee Pension Individual Retirement Arrangement) is a retirement plan that lets self-employed people and small business owners contribute up to 25% of net self-employment income. It's one of the easiest retirement plans to set up.

How SEP IRA Contributions Work

You contribute as the employer only — there are no employee deferrals. For 2026:

• Maximum contribution: The lesser of $70,000 or 25% of your net self-employment earnings (after deducting half of your self-employment tax).
• All contributions are tax-deductible and lower your adjusted gross income.

Key Features

• No Roth option: All SEP IRA contributions are traditional (pre-tax).
• No loans allowed.
• Works if you have employees: If you contribute to your SEP IRA, you must contribute the same percentage to all eligible employees who worked for you in at least 3 of the past 5 years.
• No annual filings required for the business owner.

Solo 401(k) vs SEP IRA: Side-by-Side Comparison

Worked Example: Who Contributes More?

Let's say you're a freelance consultant who earned $90,000 in net self-employment income in 2026 (after business expenses). You're 40 years old.

Solo 401(k) Scenario

1. Employee deferral: $23,500 (the max).
2. Employer contribution: 25% of ($90,000 - $6,358 SE tax deduction - $23,500) = 25% of $60,142 = $15,035.
3. Total contribution: $23,500 + $15,035 = $38,535.

SEP IRA Scenario

1. Employer contribution only: 25% of ($90,000 - $6,358) = 25% of $83,642 = $20,910.

The Solo 401(k) lets you contribute $17,625 more because of the employee deferral.

When SEP IRA Wins

If you earned $280,000+ in net self-employment income, both plans hit the $70,000 limit. At that point, the SEP IRA's simplicity may make it more attractive unless you want the Roth or loan features.

Which Plan Is Better for You?

Choose a Solo 401(k) if:

• You earn less than $280,000 and want to maximize contributions with the employee deferral.
• You want Roth contribution options to diversify your tax strategy.
• You might need to borrow from your retirement for business expenses or emergencies.
• You're 50+ and want catch-up contributions — the extra $7,500 employee deferral adds up fast.
• You have no employees and don't plan to hire any (except your spouse).

Choose a SEP IRA if:

• You want the simplest possible setup — open an account, contribute, done.
• You have or plan to hire W-2 employees — you can include them in the plan.
• You earn $280,000+ in net income and will hit the contribution limit either way.
• You don't want to file Form 5500-EZ if your balance grows past $250,000.
• You already have a traditional or Roth IRA and want to consolidate retirement accounts at the same brokerage.

Common Mistakes to Avoid

Overcontributing to a Solo 401(k)

The IRS calculates the employer contribution limit based on net self-employment income after deducting half of your self-employment tax and your employee deferrals. Many freelancers forget this step and overcontribute. Use IRS Publication 560 or a payroll calculator to confirm your limit.

Not Making Contributions by the Deadline

Both plans let you contribute up to your business tax return deadline, including extensions. If you file on April 15, 2027, you can still make 2026 contributions until then. If you extend to October 15, 2027, you have until that date. Don't miss it.

Opening a Solo 401(k) Then Hiring Employees

If you hire a full-time W-2 employee (other than your spouse), you can't keep the Solo 401(k). You'll need to freeze it and switch to a different plan like a standard 401(k) or SIMPLE IRA. Plan ahead if you're thinking about hiring.

Forgetting to File Form 5500-EZ

If your Solo 401(k) balance exceeds $250,000 at the end of the year, you must file Form 5500-EZ by July 31 of the following year (or October 15 with an extension). The penalty for not filing can be $250 per day. Mark your calendar.

Ignoring State Tax Implications

Most states follow federal rules and let you deduct Solo 401(k) and SEP IRA contributions. But a few states (like California with certain rules) may treat retirement contributions differently. Check with a CPA if you're in a high-tax state.

People Also Ask

Can I have both a Solo 401(k) and a SEP IRA at the same time?

No. If you're self-employed and already contributing to a Solo 401(k), you can't also contribute to a SEP IRA for the same business in the same year. The IRS treats them as overlapping plans. However, if you have a W-2 job with a 401(k), you can still open a Solo 401(k) for your side business — the employer contribution limits are separate, though employee deferrals are combined across all 401(k)s.

Do I need an EIN to open a Solo 401(k) or SEP IRA?

For a Solo 401(k), most brokers require an EIN (Employer Identification Number) — even if you're a sole proprietor. For a SEP IRA, you can usually open one with just your Social Security Number if you're a sole proprietor, but an EIN makes record-keeping cleaner. Getting an EIN is free and takes 10 minutes at irs.gov.

Can I convert a Solo 401(k) or SEP IRA to a Roth IRA?

Yes. You can convert funds from either plan to a Roth IRA, but you'll owe ordinary income tax on the converted amount in the year you do it. This strategy works well in low-income years. Note that only Solo 401(k)s allow direct Roth contributions — SEP IRAs don't.

What happens to my Solo 401(k) if I go back to a W-2 job?

You can keep the Solo 401(k) open and let it grow tax-deferred. You just can't make new contributions unless you have self-employment income. You can roll it over to your new employer's 401(k) or into a traditional IRA if you prefer to consolidate accounts.

Which plan has better investment options?

Both plans offer the same flexibility — you choose your brokerage and can invest in stocks, bonds, ETFs, mutual funds, and sometimes alternative assets if you open a self-directed account. The investment options depend on where you open the account, not the plan type.

Can I contribute to a Solo 401(k) or SEP IRA if I have a full-time job with a 401(k)?

Yes, if you have self-employment income on the side. The employer contributions (profit-sharing) are separate, so you can max out both. However, your employee deferrals across all 401(k) plans are capped at $23,500 total for 2026 ($31,000 if 50+). So if you defer $15,000 at your W-2 job, you can only defer $8,500 more to your Solo 401(k).

Which Plan Wins?

For most freelancers earning under $280,000, the Solo 401(k) offers higher contribution limits and more flexibility — especially if you're under 50 and want that $23,500 employee deferral. If you value simplicity, already have employees, or don't need the Roth or loan features, the SEP IRA is faster to set up and easier to maintain.

Run the numbers for your specific income using the example above. If you're still unsure, talk to a CPA who works with self-employed clients — they can model both scenarios with your actual tax situation. Ready to open an account? Check out our guides to the best Solo 401(k) providers and SEP IRA brokerages for freelancers.