Solo 401(k) vs. SEP IRA: The Self-Employed Retirement Decision

6 min read

Retirement Planning

If you're self-employed — freelancer, consultant, gig worker, or solo business owner — nobody is setting up a retirement plan for you. You have to do it yourself, and the three main options are a Solo 401(k), a SEP IRA, and a SIMPLE IRA. They sound similar but differ sharply on how much you can save and how much paperwork is involved.

The Three Options at a Glance

	Solo 401(k)	SEP IRA	SIMPLE IRA
Best for	Solo owner (or owner + spouse)	Any self-employed, esp. high earners	Small businesses with a few employees
2026 max	Up to $72,000	Up to $72,000	$17,000
Who contributes	You (as employee + employer)	Employer (that's you)	You + optional employer match
Roth option	Yes	No	No (traditional only)
Paperwork	More (Form 5500 over $250k)	Minimal	Low
Loans allowed	Yes	No	No

How the Limits Actually Work

The numbers that matter in 2026:

Solo 401(k) lets you wear two hats. As the employee, you can defer up to $24,000 (plus a $7,500 catch-up if you're 50+). As the employer, you can add a profit-sharing contribution of up to 25% of your compensation. The two combined cap at $72,000 (or $79,500 with catch-up). This lets a moderate earner contribute a higher percentage of income than any other plan.

SEP IRA is simpler but one-sided: only the employer side contributes, up to 25% of compensation, capped at $72,000. For most solo owners that effectively means ~20% of net self-employment earnings (the 25% applies after the contribution itself is subtracted). No employee deferral, no Roth, no catch-up.

SIMPLE IRA is the "small business with employees" option: you contribute up to $17,000 (plus a $3,500 catch-up), and you must either match employee contributions or make a flat 2% contribution. It's cheap to run but has much lower limits.

The Rule of Thumb

High earner, no employees? SEP IRA or Solo 401(k) both get you to $72,000. The tiebreaker is usually paperwork tolerance and the Roth option.
Want to maximize at lower income? Solo 401(k) wins. At $100,000 of self-employment income, a Solo 401(k) can shelter the full $24,000 deferral plus ~$18,600 in profit-sharing, while a SEP IRA is limited to ~$18,600 total. The Solo 401(k) lets you save more, faster.
Want a Roth and backdoor Roth compatibility? Solo 401(k) (with a Roth option) is your only choice among the three. SEP and SIMPLE IRAs also interfere with the backdoor Roth IRA's pro-rata rule because they're counted as pre-tax IRA balances.
Have a few employees? Stop. Neither a Solo 401(k) nor a SEP IRA works once you have eligible employees (a SEP requires you to contribute for them too). That's SIMPLE IRA territory, or a full 401(k).

The Catch

Solo 401(k)s require more setup (a plan document, an EIN, and once plan assets exceed $250,000, an annual Form 5500-EZ). SEP IRAs require essentially no ongoing administration — open the account and contribute. If you expect to add employees soon, starting a Solo 401(k) today means unwinding it later.

The deadline matters too. SEP IRAs can be opened and funded up to your tax filing deadline (including extensions). Solo 401(k)s must be established by December 31 of the tax year — though contributions can be made until the filing deadline.

What This Means for You

If you're a solo operator, the answer is usually a Solo 401(k) — it lets you save more at most income levels, gives you a Roth option, and keeps the backdoor Roth open. A SEP IRA is the right call when you want maximum simplicity and are a high earner who values the least possible paperwork. A SIMPLE IRA only makes sense once you have employees.