Solo 401(k) Contribution Calculator
Find your maximum 2026 solo 401(k) contribution: the $24,500 employee deferral, the 20% or 25% employer profit-sharing, catch-up at 50+ ($11,250 at 60–63), the $72,000 cap, a spouse, a SEP-IRA comparison and your tax saving.
How it works
Sole proprietor: earned income = net profit − ½ SE tax (SE tax = 15.3% × 92.35% of profit, Social Security part to $184,500) · Employer share = 20% × earned income · Corporation: employer share = 25% × W-2 salary (pay counted up to $360,000) · Employee deferral ≤ $24,500 (+$8,000 at 50+, +$11,250 at 60–63) · Deferral + employer ≤ $72,000 and ≤ earned income
A solo 401(k) (also called an individual or one-participant 401(k)) lets you contribute in two roles. As the employee you can defer up to $24,500 of pay in 2026, plus an $8,000 catch-up from age 50 — or $11,250 if you are 60 to 63. As the employer your business can add profit-sharing: 25% of W-2 salary for an S or C corporation, or for a sole proprietor or single-member LLC 20% of net profit after subtracting half of the self-employment tax (the 25% rate applied to pay after the contribution itself). Deferrals plus profit-sharing cannot exceed $72,000, not counting catch-up, and cannot exceed what you earned. The employee limit is per person, so deferrals at a day job reduce it, but the $72,000 cap is per employer. A SEP-IRA offers only the employer part, which is why a solo 401(k) usually allows much more at moderate incomes; the table and chart show both across income levels. If your spouse is paid by the business, they get their own set of limits.
Worked example
A sole proprietor under 50 with $90,000 of net profit pays $12,717 of self-employment tax (15.3% of $83,115), so earned income is $90,000 − $6,358 = $83,642. The employee deferral is the full $24,500 and the employer share is 20% × $83,642 = $16,728, for a $41,228 maximum — $24,500 more than a SEP-IRA. An S-corporation owner aged 61 with a $100,000 salary can defer $24,500, add $25,000 (25%) of profit-sharing and an $11,250 catch-up: $60,750.
Sources: IRS Notice 2025-67 — 2026 retirement plan limits · IRS — 401(k) limit increases to $24,500 for 2026 · IRS — One-participant 401(k) plans · IRS Publication 560 — Retirement plans for small business (self-employed rate worksheet)
Frequently asked questions
What is the 2026 solo 401(k) limit?
Employee deferrals are capped at $24,500, and total contributions (deferrals plus employer profit-sharing) at $72,000. Catch-up contributions come on top: $8,000 from age 50, or $11,250 at ages 60 to 63, so the most anyone can put in is $83,250. Every contribution is also limited by what the business actually paid you or earned.
How does a solo 401(k) beat a SEP-IRA?
Both allow the same employer contribution — 20% of a sole proprietor’s earned income or 25% of a corporation owner’s salary — but a solo 401(k) adds the employee deferral on top. At $90,000 of profit that is about $41,200 versus $16,700. At very high incomes both reach the $72,000 cap, though the 401(k) still allows catch-up contributions.
I also have a 401(k) at my day job. Can I still contribute?
Yes. The $24,500 employee deferral is shared across all plans, so enter what you defer at work under More options. Employer profit-sharing in your own business has its own $72,000 cap and is not reduced by your day-job plan.
Should my contributions be Roth or traditional?
Traditional contributions lower this year’s taxable income; Roth contributions are taxed now but withdrawals in retirement are tax-free. From 2026, catch-up contributions must be Roth if your FICA wages from the employer were over $150,000 the year before — this applies to corporation owners, not to sole proprietors, whose self-employment income is not FICA wages.
Can I have a solo 401(k) with employees?
Only if the employees are your spouse or are excludable (for example, part-time workers under the plan’s service rules). Once you have eligible non-spouse employees, the plan must cover them and becomes a regular 401(k) with testing rules.
Related calculators
Educational estimate using 2026 IRS limits (Notice 2025-67) and the Publication 560 method — not tax advice. Plan documents, other plans and your full tax situation can change the result; confirm with your plan provider or a tax professional.