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How much can I put in a Solo 401(k)?

Tell us how your business is taxed, what it earned or paid you, and your age. You’ll see the most you can contribute for 2026 as employee and employer, and how that compares with a SEP IRA. Learn how the account works on our Solo 401(k) guide.

Educational only, not financial advice

This tool shows general math, not a recommendation for you. It isn’t financial, tax or legal advice, and real returns, fees and tax rules will differ. Talk to a qualified professional before making decisions. What you enter stays in your browser: nothing is saved or sent to us.

How is your business taxed?

Sole proprietor, single-member LLC or partnership: you pay self-employment tax.

$

Schedule C net profit for 2026, before retirement contributions.

Catch-ups start at 50; ages 60 to 63 get a higher one.

$

What you put in a day job’s 401(k), 403(b) or SIMPLE this year. Your deferral limit is shared.

2026 maximum, estimated

You could put in up to $43,087

As both employee and employer.

Employee deferral

$24,500

Employer contribution

$18,587

Total

$43,087

SEP IRA max, same income

$18,587

A Solo 401(k) lets you put in $24,500 more than a SEP IRA would, because a SEP has no employee deferral.

How we calculated this

Following the IRS Publication 560 Deduction Worksheet for Self-Employed, with a 25% plan rate:

Net profit (Schedule C)$100,000
Net earnings subject to SE tax (× 92.35%)$92,350
Self-employment tax12.4% Social Security up to the wage base, plus 2.9% Medicare$14,130
Minus half of SE tax (deduction)$7,065
Net earnings for the plan (step 3)$92,935
20% of net earnings (step 5)25% plan rate ÷ 1.25 = 20%$18,587
Employee deferral used (step 9)$24,500
Half of net earnings minus deferral (step 12)$34,218
Employer profit-sharing (step 13, smallest of 20%, overall limit minus deferral, step 12)$18,587
Employee deferral allowed (step 15)$24,500
Catch-up allowed (step 18)$0
Total (step 19)$43,087

2026 limits: $24,500 employee deferral, $72,000 overall, compensation counted up to $360,000. Amounts are rounded to the dollar.

Advanced(optional)
$

Wages already taxed for Social Security reduce the SE tax on your business income (Schedule SE). Only matters if the total passes the $184,500 wage base.

Assumptions and sources

  • 2026 limits. Employee deferrals up to $24,500, plus a $8,000 catch-up at 50 or older ($11,250 at ages 60 to 63). Employee and employer contributions together can’t pass $72,000, not counting catch-ups, and only the first $360,000 of compensation counts.
  • Sole proprietors and single-member LLCs. We follow the Deduction Worksheet for Self-Employed in IRS Publication 560 with a 25% plan rate. Your compensation is net profit minus half your self-employment tax, and the employer contribution is 20% of that (25% ÷ 1.25). Self-employment tax is figured as on Schedule SE: 92.35% of net profit, 12.4% Social Security up to the $184,500 wage base and 2.9% Medicare.
  • S-corp owners. Only W-2 salary counts. The employer contribution is up to 25% of salary, and deferrals plus employer contributions can’t exceed your salary.
  • Other jobs. Your employee deferral limit, and the age-50 catch-up, are per person: deferrals to any other 401(k), 403(b) or SIMPLE plan count against them. A 457(b) plan has its own separate limit.
  • Roth catch-ups. From 2026, if your prior-year wages from the business paying your catch-up were over $150,000, catch-ups must go in as Roth.
  • Not modeled: partnerships with several partners, more than one business, a spouse in the plan, or a plan rate below 25%. Your inputs aren’t sent to us.

Results are estimates for education only, not financial, tax or legal advice. Confirm with a tax professional.

Sources

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