Which saves more tax, a SEP IRA or a Solo 401k?

For most self-employed workers earning under $300,000, the Solo 401k saves more because it adds a $23,000 employee deferral on top of the employer contribution. At $100,000 of profit a Solo 401k allows roughly $43,000 while a SEP IRA allows only about $18,000. Above roughly $300,000, both plans max out at $69,000.

Do SEP IRA and Solo 401k have the same 2026 contribution limit?

Yes, both are capped at $69,000 for 2026. The difference is how you get there. A SEP IRA is employer-only at 25% of compensation. A Solo 401k stacks a $23,000 employee deferral with the employer contribution, which lets you reach the cap at a lower income level.

Is a SEP IRA easier to set up than a Solo 401k?

Yes. A SEP IRA takes about five minutes to open at any major brokerage using Form 5305-SEP, with no annual IRS reporting. A Solo 401k requires a plan document, must be established by December 31 to make employee deferrals, and requires Form 5500-EZ once the balance exceeds $250,000.

Can I have both a SEP IRA and a Solo 401k?

You can, but the $69,000 Section 415(c) limit is shared across both plans for the same employer. Contributing to both does not double the cap. Most freelancers pick one to avoid the contribution-tracking complexity.

SEP IRA vs Solo 401k 2026: Which Retirement Plan Saves More Tax? | Cashbizly

Same Cap, Very Different Math

On paper, the SEP IRA and the Solo 401k look identical for 2026: both cap total contributions at $69,000. That headline number misleads a lot of freelancers into thinking the choice does not matter. It does. The Solo 401k lets you reach a much bigger deduction at moderate income because it has a second contribution bucket the SEP IRA lacks.

The deciding factor is almost always your profit level. Below roughly $300,000, the Solo 401k wins. Above it, they tie — and the SEP IRA wins on simplicity.

How Each Plan Builds the Contribution

A SEP IRA is employer-only. Your business contributes up to 25% of your compensation (roughly 20% of net SE earnings for a sole proprietor after backing out the contribution and half of SE tax). There is no employee deferral, no Roth option, and no loan provision.

A Solo 401k has two buckets. You get the same employer profit-sharing of up to 25% of compensation, plus a flat $23,000 employee elective deferral ($30,500 if 50+). The two stack up to the $69,000 cap. That flat employee deferral is the entire reason the Solo 401k pulls ahead at lower incomes.

Side-by-Side at Three Income Levels (Under 50)

Net SE Profit	SEP IRA (≈20%)	Solo 401k (Emp + Emp)	Extra Deduction
$80,000	$14,000	$37,000	$23,000
$150,000	$26,500	$49,500	$23,000
$300,000	$46,000	$69,000 (capped)	$23,000
$400,000	$69,000 (capped)	$69,000 (capped)	$0

The pattern is clear. At every income level below the cap, the Solo 401k allows exactly $23,000 more — the employee deferral the SEP IRA cannot offer. At $150,000 of profit, that is an extra $5,500 of federal tax savings at the 24% bracket. Only at very high profit do the two plans converge on the same $69,000 ceiling.

Pro Tip: If your net profit lands between $40,000 and $250,000, the Solo 401k is almost always the right call. The flat $23,000 employee deferral does not care whether you earned $50,000 or $250,000 — you get the full amount either way, as long as you earned at least $23,000. The SEP IRA, by contrast, scales with income and leaves lower earners with a much smaller deduction.

Where the SEP IRA Still Wins

The SEP IRA has three genuine advantages, and I still recommend it for specific clients. First, setup is genuinely five minutes — sign Form 5305-SEP at any brokerage and you are done. Second, there is no Form 5500-EZ filing ever, regardless of balance. Third, you can adopt and fund a SEP IRA as late as your extended filing deadline (October 15, 2027 for 2026), which makes it the best last-minute deduction if you forgot to plan ahead.

The Solo 401k, by contrast, must be established by December 31, 2026 to make any 2026 employee deferrals. If you are reading this in March 2027 and want a 2026 deduction, the SEP IRA is your only option.

Other Differences That Matter

Roth option: Solo 401k only. SEP IRAs are pre-tax only (though you can convert to Roth separately).
Loans: Solo 401k allows loans up to $50,000. SEP IRAs do not.
Employees: If you ever hire full-time employees, a SEP IRA forces you to contribute for them at the same percentage. A Solo 401k has the same obligation but more flexibility on entry requirements.
Catch-up: Solo 401k adds $7,500 at 50+. SEP IRAs have no catch-up — the cap stays $69,000 regardless of age.

Compliance Warning: If you have employees now or plan to hire within a year, neither plan is truly "solo." Both require employer contributions for eligible employees at the same rate you contribute for yourself. A single $40,000 employee can turn a $69,000 personal deduction into a $100,000+ employer cost. Model the headcount cost before adopting either plan.

The Bottom Line

Pick the Solo 401k if your profit is under roughly $300,000 and you can establish the plan by December 31 — the extra $23,000 employee deferral is the single biggest retirement tax break available to freelancers. Pick the SEP IRA if you want a five-minute setup, no IRS filings, or a last-minute 2026 deduction you can still make by October 15, 2027. Run your projected deduction through the Self-Employment Tax Calculator and confirm eligible contributions with the Tax Deduction Finder before you fund.

SEP IRA vs Solo 401k 2026: Which Retirement Plan Saves More Tax?