Solo 401(k) Contribution Calculator 2026
Estimate your maximum 2026 Solo 401(k) contribution from self-employment or S-corp income: employee deferral, employer share, catch-up, and tax savings.
Solo 401(k) Contribution Calculator 2026
Business Type
Sole proprietors and partnerships use net SE earnings; S-corps and C-corps use W-2 wages.
Net Self-Employment Earnings
Schedule C net profit (or partnership SE earnings) before the SE-tax deduction.
S-Corp W-2 Wages
Reasonable W-2 compensation (Box 1 plus pre-tax deferrals), not distributions.
Your Age (end of 2026)
Drives the catch-up tier: $8,000 at 50-59 or 64+, $11,250 at 60-63.
Deferrals Already Made Elsewhere
Elective deferrals into another employer's 401(k)/403(b) this year. The $24,500 limit is per person.
Marginal Tax Rate
Your federal marginal bracket, used for the estimated tax-savings figure.
Deferral plus employer was capped at the $72,000 annual additions limit.
Estimates only, not tax or legal advice. Tax-savings applies to traditional (pre-tax) contributions; Roth deferrals are not pre-tax deductible. State income tax is not included.
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Tax47 covers federal and state taxes, deductions, credits, and refund estimates for all 50 states.
How the Solo 401(k) Calculator Works
A Solo 401(k) (also called an individual 401(k) or one-participant 401(k)) lets a self-employed person wear two hats at once. You contribute as the employee, deferring part of your pay, and your business contributes as the employer, making a profit-sharing contribution on top. That dual role is why a Solo 401(k) can hold far more than an IRA: the two contributions stack.
This calculator applies the 2026 IRS limits for you. Pick your business type, enter your net self-employment earnings (for a sole proprietor or partnership) or your W-2 wages (for an S-corp or C-corp), set your age, and note any 401(k) deferrals you've already made at another job. From there it works out the employee deferral, the employer contribution, the catch-up tier for your age, and the combined total, capped where the rules require.
The employer piece trips up most people, so the tool handles the circular sole-proprietor math for you (more on that below) and keeps the W-2 path clean for incorporated filers.
2026 Solo 401(k) Contribution Limits
All figures come from IRS Notice 2025-67, the cost-of-living adjustments effective January 1, 2026.
| Limit | 2026 Amount | Code Reference |
|---|---|---|
| Employee elective deferral | $24,500 | 402(g) |
| Age 50-59 / 64+ catch-up | $8,000 | 414(v) |
| Age 60-63 super catch-up | $11,250 | 414(v)(2)(E) |
| Annual additions cap (excl. catch-up) | $72,000 | 415(c) |
| Annual compensation cap | $360,000 | 401(a)(17) |
Because the catch-up sits on top of the $72,000 annual additions cap, the combined maximum depends on your age:
| Age in 2026 | Combined Maximum (deferral + employer + catch-up) |
|---|---|
| Under 50 | $72,000 |
| 50-59 or 64+ | $80,000 |
| 60-63 (super catch-up) | $83,250 |
You reach these ceilings only if your earned income is high enough to support the employer contribution. Most filers land below the cap, which is why this calculator works from your actual compensation instead of just quoting the headline number.
Sole Proprietor vs. S-Corp: How the Employer Contribution Is Calculated
Both paths nominally use a 25% employer rate, yet they reach very different numbers because of how compensation is defined.
Sole proprietor or partnership: 20% of net SE earnings
For a sole proprietor, the employer contribution reduces your own compensation, so applying 25% directly would be circular. IRS Publication 560 resolves it with an effective rate of 20% applied to net self-employment earnings after the half-SE-tax deduction. The steps: take net Schedule C profit, multiply by 0.9235 to get net earnings from self-employment, work out the self-employment tax (12.4% Social Security up to the 2026 wage base of $184,500, plus 2.9% Medicare on all of it), subtract half of that SE tax, cap the result at $360,000, then take 20%.
Worked example: $100,000 of net Schedule C profit yields roughly $92,350 of net SE earnings, about $14,130 of SE tax, and a compensation base near $92,935. Twenty percent of that is about $18,587 of employer contribution, on top of your $24,500 employee deferral.
S-corp or C-corp: 25% of W-2 wages
An incorporated business pays you a W-2 wage that doesn't shift when the contribution is made, so the full 25% applies directly to those wages (capped at $360,000), with no half-SE-tax adjustment since FICA is already handled through payroll. On $100,000 of W-2 wages, the employer contribution is a clean $25,000. That's why the same dollar of income often produces a larger employer contribution as an S-corp, though payroll taxes and reasonable-compensation rules complicate the comparison.
Solo 401(k) Tax Savings and How It Fits Your Return
Traditional (pre-tax) Solo 401(k) contributions reduce your taxable income for the year, so the federal savings is roughly your contribution times your marginal rate. A $40,000 traditional contribution at a 24% bracket trims about $9,600 off your federal tax. Roth Solo 401(k) deferrals don't get a current deduction, so the tax-savings figure here applies to traditional contributions only, and state income tax may add more on top.
Because the employer contribution depends on income net of self-employment tax, it's worth running the Self-Employment Tax Calculator first, then checking how the QBI deduction interacts with the lower taxable income. If you're comparing retirement vehicles, the Traditional IRA Deduction Calculator shows where an IRA fits alongside a Solo 401(k), and the Estimated Quarterly Tax Calculator helps you adjust your quarterly payments once the deduction lowers your bill.
These results are estimates only and not tax or legal advice. For a full federal and state picture across all 50 states, download Tax47 to assemble your complete return.
Frequently Asked Questions
Common questions about solo 401(k) contribution calculator 2026
How much can I contribute to a Solo 401(k) in 2026?
For 2026, the combined Solo 401(k) limit is $72,000 (the 415(c) annual additions cap covering employee deferral plus employer profit-sharing). A catch-up applies on top of that: $8,000 if you're 50-59 or 64+, or $11,250 if you're 60-63. So the practical maximum is $72,000 under 50, $80,000 at 50-59 or 64+, and $83,250 at 60-63. Your real maximum depends on your earned income, since the employer piece is a percentage of compensation.
What is the difference between the employee deferral and the employer profit-sharing contribution?
A Solo 401(k) lets you contribute as two people. As the employee, you can defer up to $24,500 in 2026 (the 402(g) elective deferral limit), regardless of business type. As the employer, your business makes a profit-sharing contribution on top: roughly 20% of net self-employment earnings for a sole proprietor, or 25% of W-2 wages for an S-corp. The two are added together and capped at the $72,000 annual additions limit, with the catch-up sitting above that.
Why is the employer contribution 20% for a sole proprietor but 25% for an S-corp?
The 25% rate is the plan's stated employer rate. For a sole proprietor, though, it's applied to compensation that is itself net of the contribution, which creates a circular calculation. IRS Publication 560 resolves that with an effective rate of 20% of net self-employment earnings (after the half-SE-tax deduction). An S-corp pays you a clean W-2 wage that doesn't change when the contribution is made, so the full 25% applies directly to those wages.
What is the Solo 401(k) catch-up contribution if I'm 50 or older, and the 60-63 super catch-up?
If you're 50-59 or 64 and older, you can add a standard catch-up of $8,000 in 2026. If you're 60, 61, 62, or 63, the SECURE 2.0 super catch-up raises that to $11,250 for those four years only. At age 64 it reverts to the standard $8,000. The catch-up sits on top of the $72,000 annual additions cap, so it's extra room rather than part of the base limit.
Can I contribute to a Solo 401(k) if I also have a 401(k) at a regular job?
Yes, but the $24,500 employee deferral limit is per person across every plan, not per plan. If you already deferred, say, $10,000 into your day job's 401(k), you have only $14,500 of deferral room left for the Solo 401(k). The employer profit-sharing contribution is separate and isn't reduced by deferrals elsewhere. Enter what you've already deferred in the 'deferrals elsewhere' field to see your remaining room.
Is a Solo 401(k) contribution tax-deductible, and how much will it save me?
Traditional (pre-tax) Solo 401(k) contributions are deductible, which lowers your taxable income for the year. The federal savings is roughly your contribution times your marginal tax rate: a $30,000 traditional contribution at a 24% bracket saves about $7,200 in federal tax. Roth Solo 401(k) deferrals are not pre-tax deductible, so the tax-savings figure here applies only to traditional contributions. State income tax may add more savings.
What counts as compensation, net self-employment earnings or gross business income?
Not gross revenue. For a sole proprietor, the calculator starts from your net Schedule C profit (net self-employment earnings before the SE-tax deduction), then subtracts half of your self-employment tax to reach the compensation base. For an S-corp, compensation is your reasonable W-2 wages (Box 1 plus pre-tax deferrals), not distributions. Compensation is capped at $360,000 for 2026 under the 401(a)(17) limit before any percentages are applied.
What is the total maximum Solo 401(k) contribution for 2026?
The 415(c) annual additions cap for deferral plus employer contributions is $72,000 in 2026. Adding the age-based catch-up gives three practical maximums: $72,000 if you're under 50, $80,000 if you're 50-59 or 64+, and $83,250 if you're 60-63. You reach these ceilings only if your earned income is high enough to support the employer contribution, so most filers land below the cap.