If you are self-employed, a freelancer, or a solo business owner, you have access to two of the most powerful retirement savings accounts available: the SEP IRA and the Solo 401(k). Both offer substantial tax deductions and high contribution limits — but they work differently and suit different situations.
Here is how to choose between a SEP IRA and a Solo 401(k) in 2026.
SEP IRA: The Basics
A SEP IRA (Simplified Employee Pension Individual Retirement Arrangement) lets self-employed people contribute up to 25% of net self-employment income, with a maximum contribution of $70,000 in 2026.
Key features:
- Contributions are made only by the employer (you), not as an employee
- Extremely simple to set up — most major brokerages offer it with one form
- No annual filing requirements (no Form 5500)
- Contributions are tax-deductible; earnings grow tax-deferred until withdrawal
- Contribution deadline: your tax filing deadline, including extensions
The simplicity of the SEP IRA makes it attractive for sole proprietors and freelancers who want a low-maintenance retirement account without administrative complexity.
Solo 401(k): The Basics
A Solo 401(k) — also called an Individual 401(k) or One-Participant 401(k) — is designed for self-employed individuals with no employees other than a spouse. It allows contributions in two roles: as both employee and employer.
2026 contribution limits:
- Employee contribution: Up to $23,500 (plus $7,500 catch-up if age 50 or older)
- Employer contribution: Up to 25% of compensation
- Combined maximum: $70,000 (or $77,500 with catch-up)
Key features:
- Higher effective contribution limits for lower-income self-employed individuals
- Optional Roth component (contributions are after-tax but grow tax-free)
- Loan provision — borrow up to 50% of the vested balance, max $50,000
- Requires IRS Form 5500-EZ filing when balance exceeds $250,000
- Must be established by December 31 of the tax year
The Critical Difference: Contribution Rates at Lower Incomes
This is where the Solo 401(k) wins decisively for many self-employed individuals. Because the SEP IRA contribution is capped at 25% of net self-employment income, lower earners can contribute significantly more to a Solo 401(k).
Example: A freelancer with $60,000 in net self-employment income:
- SEP IRA maximum: 25% × $60,000 = $15,000
- Solo 401(k) maximum: $23,500 employee + 25% × $60,000 employer = $38,500
The Solo 401(k) allows more than double the contribution at this income level — which means a significantly larger tax deduction and faster retirement wealth accumulation.
At higher incomes (above ~$280,000), both accounts approach the same maximum contribution limit and the advantage narrows.
SEP IRA vs Solo 401(k): When to Choose Each
Choose a SEP IRA if:
- You have employees other than a spouse (Solo 401(k)s are only for owner-only businesses)
- You want maximum simplicity with no annual filings
- Your self-employment income is high enough that 25% of net income already hits or approaches the $70,000 cap
- You missed the December 31 deadline to open a Solo 401(k) for the current tax year
Choose a Solo 401(k) if:
- Your self-employment income is under $200,000 and you want to maximize contributions
- You want a Roth option for after-tax contributions
- You want the ability to take a loan from your retirement account
- You are 50 or older and want to use catch-up contributions
Can You Have Both?
Yes — but combined contributions across all employer-sponsored plans cannot exceed the $70,000 annual limit. If you have both a W-2 job (with a 401(k)) and self-employment income, you can use a SEP IRA for the self-employment income, but the Solo 401(k) employee contribution limit applies across all 401(k)-type plans you participate in.
Tax Treatment
Both accounts offer the same traditional tax structure: contributions reduce taxable income today, and the money grows tax-deferred until retirement. Withdrawals in retirement are taxed as ordinary income.
The Solo 401(k) adds the option for Roth contributions — after-tax money that grows tax-free and is withdrawn tax-free in retirement. There is no Roth equivalent for SEP IRAs (though a SEP IRA can be converted to a Roth IRA separately).
How to Open Each Account
SEP IRA: Available at virtually any brokerage or bank. Complete IRS Form 5305-SEP (or the brokerage’s own agreement) and open the account. No special setup requirements.
Solo 401(k): Available at Fidelity, Vanguard, Schwab, and other major brokerages. You must establish the plan (sign plan documents) by December 31 of the year you want to make contributions for. Contributions themselves can be made up to the tax filing deadline.
Bottom Line
For most self-employed individuals earning under $200,000, the Solo 401(k) is the better choice — it allows significantly larger tax-deductible contributions and includes a Roth option. The SEP IRA wins on simplicity and is the right tool when you have employees, missed the Solo 401(k) setup deadline, or have income high enough that the 25% cap approaches the annual maximum. Whichever you choose, contribute the maximum you can afford — the tax deduction today and the tax-deferred growth over decades are among the most powerful wealth-building tools available to self-employed workers.