Solo 401(k) Calculator
Calculate your exact 2026 solo 401(k) contribution limit — the $24,500 employee deferral, the 20-25% employer piece, and catch-ups up to $11,250 — for sole proprietors, single-member LLCs, and S-corp owners. Compare against a SEP IRA and see your income-tax savings.
Reviewed by Slava Akulov, CEO & Co-Founder at Jupid · Last updated: August 2026
Schedule C filers. Contributions are based on net earnings after ½ SE tax.
Schedule C net profit after business expenses.
50+ adds an $8,000 catch-up; turning 60-63 in 2026 raises it to $11,250.
Used only for the income-tax-savings estimate.
Maximum contribution
$43,087
employee + employer
Est. income-tax savings
$7,814
at your 22% marginal bracket
How Your Limit Is Built
| Net profit (Schedule C) | $100,000 |
| − ½ self-employment tax | −$7,065 |
| = Net earnings (plan compensation) | $92,935 |
| Employee deferral (up to $24,500) | $24,500 |
| Employer piece (~20% of net earnings) | $18,587 |
| Total solo 401(k) — 2026 | $43,087 |
| SEP IRA max (same income) | $18,587 |
Deduct it right — and find the write-offs you're missing
Jupid tracks your self-employed income, deductions, and quarterly taxes year-round.
Solo 401(k) vs SEP
+$24,500
Annual additions cap
$72,000
% of income saved
43%
Deadlines for 2026
Employee deferrals generally require the plan (and your deferral election) to exist by December 31, 2026 — S-corp owners must run deferrals through payroll during the year. A sole proprietor opening their first plan gets a SECURE 2.0 grace period to April 15, 2027 (no extensions). The employer piece can be contributed until your filing deadline, including extensions.
Estimates for tax year 2026 using the standard deduction and 2026 federal brackets. Pre-tax contributions reduce income tax only — never the 15.3% SE tax or FICA. The savings estimate ignores state tax and the QBI interaction (retirement deductions also shrink your 20% QBI deduction, so real savings can be somewhat lower). Not tax advice.
How the Solo 401(k) Math Works
Find your plan compensation
Sole proprietors start from Schedule C net profit and subtract half their self-employment tax to get net earnings. S-corp owners simply use W-2 wages — K-1 distributions never count.
Stack both contribution hats
As the employee you defer up to $24,500 (plus catch-ups from age 50). As the employer you add 25% of wages — or about 20% of net earnings when self-employed, because the contribution reduces its own base.
Apply the 2026 caps
Deferral + employer piece together can't exceed the lesser of $72,000 or 100% of compensation. Catch-ups ($8,000, or $11,250 for ages 60-63) go on top — up to $83,250 total.
Who Can Open a Solo 401(k)
Any business with self-employment income and no full-time employees other than an owner and their spouse:
Freelancers & sole proprietors
Schedule C filers — consultants, creators, gig workers, and independent contractors, even with a W-2 day job on the side.
Single-member LLCs
Default-taxed LLCs use the same net-earnings math as sole proprietors. Partners in a partnership use their K-1 self-employment earnings.
S-corp owner-employees
Contributions key off your W-2 salary: defer up to $24,500 from wages, and the corporation adds up to 25% of those wages.
Working spouses
A spouse earning income from the same business gets their own full set of limits — without breaking the one-participant rule.
Hiring a full-time employee who isn't your spouse ends solo 401(k) eligibility — the plan must then cover employees under normal 401(k) rules.
Solo 401(k) vs SEP IRA in 2026
Both use the same employer formula — the solo 401(k) adds the employee deferral and catch-ups on top, while the SEP wins on simplicity and its after-year-end deadline. Run the SEP side in our SEP IRA Calculator.
| Feature | Solo 401(k) | SEP IRA |
|---|---|---|
| 2026 contribution formula | $24,500 employee deferral (up to 100% of compensation) + employer piece of 25% of W-2 wages or ~20% of net self-employment earnings | Employer-only: 25% of W-2 wages or ~20% of net self-employment earnings |
| 2026 maximum (under 50) | $72,000 | $72,000 — but you need ~$360,000 of compensation to reach it |
| Catch-up contributions | $8,000 at age 50+; $11,250 for ages 60-63 (up to $83,250 total) | None |
| Advantage at lower incomes | Big — at $50,000 of sole-prop profit you can put away roughly $33,800 thanks to the deferral | At $50,000 of sole-prop profit the max is only about $9,300 |
| Roth option | Yes — Roth solo 401(k) deferrals are widely available | Allowed since SECURE 2.0 (2023), but few providers actually offer Roth SEP accounts |
| Deadline to establish | By Dec 31 for employee deferrals (SECURE 2.0 lets a sole proprietor's first-year plan be adopted by the filing deadline, without extensions); employer piece can be added until the extended filing deadline | Any time up to your tax-filing deadline, including extensions |
| Deadline to fund for 2026 | Deferrals through payroll/year-end elections; employer contributions by the filing deadline + extensions | Filing deadline + extensions (as late as Oct 15, 2027) |
| Loans allowed | Yes — up to 50% of the balance, max $50,000 | No |
| IRS paperwork | Form 5500-EZ each year once plan assets exceed $250,000 | None — no annual filing |
| Employees | Only for owner (+ spouse); hiring a full-time non-spouse employee ends eligibility | Works with employees, but you must contribute the same percentage for every eligible employee |
What This Calculator Includes
Real self-employed math
Net profit → SE tax (12.4% Social Security up to $184,500 + 2.9% Medicare) → ½-SE deduction → net earnings — the exact Pub 560 worksheet chain.
Every 2026 limit
The $24,500 deferral, $8,000 and $11,250 catch-ups, $72,000 §415(c) cap, and $360,000 compensation cap from IRS Notice 2025-67.
Entity-aware results
Sole prop / single-member LLC uses ~20% of net earnings; S-corp owners get 25% of W-2 wages with no SE-tax adjustment.
SEP IRA side-by-side
Your SEP maximum at the same income, so you can see exactly what the employee deferral and catch-ups are worth.
Why Use This Calculator?
The 20% vs 25% trap
Most people multiply net profit by 25% and overshoot their real limit. The self-employed rate is effectively 20% of net earnings after the ½-SE-tax deduction — this calculator gets the circular math right.
Catch-ups done correctly
The SECURE 2.0 ages-60-63 catch-up ($11,250) and the regular age-50 catch-up ($8,000) are applied by your exact age — and correctly excluded from the $72,000 annual-additions cap.
See the tax payoff
Every dollar contributed pre-tax comes off your taxable income. The calculator prices your maximum at 2026 federal brackets — and is honest that SE tax doesn't change.
Frequently Asked Questions
Solo 401(k) contribution limits for 2026
A solo 401(k) (the IRS calls it a one-participant 401(k)) lets a self-employed person contribute in two capacities at once. As the employee, you can defer up to $24,500 in 2026 — 100% of compensation if you earn less than that. As the employer, the business adds up to 25% of W-2 wages, or about 20% of net self-employment earnings for sole proprietors and single-member LLCs. Together, non-catch-up contributions are capped at the lesser of $72,000 or 100% of compensation (IRC §415(c), per IRS Notice 2025-67).
| 2026 limit | Amount |
|---|---|
| Employee deferral (§402(g)) | $24,500 |
| Catch-up, age 50+ | $8,000 |
| Higher catch-up, ages 60-63 (SECURE 2.0) | $11,250 |
| Total defined-contribution cap (§415(c)) | $72,000 (excl. catch-ups) |
| Absolute maximum (ages 60-63) | $83,250 |
| Compensation cap (§401(a)(17)) | $360,000 |
Example: a 40-year-old sole proprietor with $100,000 of net profit pays $14,130 of SE tax, leaving $92,935 of net earnings. Their maximum is $24,500 + 20% × $92,935 = $43,087 — versus only $18,587 in a SEP IRA at the same income.
Why the self-employed employer piece is 20%, not 25%
For W-2 employees the employer contribution is a flat 25% of wages. For the self-employed, the limit is 25% of compensation after subtracting the contribution itself (and half your SE tax). Solving that circular definition gives the shortcut the IRS publishes in Pub 560: multiply net earnings by 25% ÷ 125% = 20%. Skipping this adjustment is the single most common solo 401(k) over-contribution mistake — and excess contributions trigger a 10% excise tax on Form 5330 until corrected.
Also remember what contributions do notchange: self-employment tax. Schedule SE runs on net earnings before any retirement deduction, so contributions save income tax only. If cutting the 15.3% SE tax is the goal, that's an entity question — see our S Corp Tax Calculator.
S-corp owners: your salary sets your ceiling
In an S-corp, only W-2 wagescount as plan compensation — K-1 pass-through income does not. A $50,000 salary caps the employer piece at $12,500 (25%), no matter how much profit flows through. That creates real tension with the S-corp's core strategy of keeping salary reasonable but modest: a lower salary saves payroll tax but shrinks your retirement room. Owners who want to max out at $72,000 need roughly $190,000 of W-2 wages ($24,500 deferral + 25% × $190,000 = $72,000). Deferrals must also run through payroll during the calendar year, so set your election early.
Official References
Sources used for the 2026 limits and rules in this calculator (verified August 2026):
- IRS IR-2025-111 / Notice 2025-67: 2026 Retirement Plan Limits
The $24,500 deferral limit, $8,000 catch-up, $11,250 higher catch-up (ages 60-63), and $72,000 defined-contribution limit for 2026.
- IRS Notice 2025-67 (full text, PDF)
The official 2026 cost-of-living adjustments, including the $360,000 compensation cap and $800 SEP minimum compensation.
- IRS: One-Participant 401(k) Plans
Who qualifies for a solo 401(k), contribution rules, and the Form 5500-EZ filing threshold.
- IRS: Calculating Your Own Retirement Plan Contribution
Why the self-employed employer rate works out to ~20% of net earnings (25% of post-contribution compensation).
- IRS Publication 560: Retirement Plans for Small Business
The Deduction Worksheet for Self-Employed and full SEP / qualified-plan rules.
- SSA: Contribution and Benefit Base
The 2026 Social Security wage base of $184,500 used in the SE-tax step.
This calculator estimates 2026 contribution limits and federal income-tax savings using the standard deduction. It does not model QBI interactions, employer aggregation across multiple businesses, or Roth vs pre-tax choices. Not tax or investment advice — confirm your limit with a tax professional before contributing.
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