Our solo 401k calculator shows your exact 2026 maximum, including employee deferrals, employer profit-sharing, and any age-50 catch-up.
A solo 401(k), also called a one-participant 401(k), lets self-employed people and business owners with no employees contribute as both the employee and the employer. That dual role is the reason the plan can shelter far more than an IRA or a SEP IRA. If you are also comparing retirement options, our FERS Retirement Calculator and Dave Ramsey Retirement Calculator can help you test the long-run results, while the 2026 Income Tax Calculator shows the tax saving behind each contribution.
Solo 401(k) Calculator (2026)
Enter your business income and age to see your maximum solo 401(k) contribution for 2026.
Table of Contents
- Solo 401(k) Contribution Rules
- 2026 Solo 401(k) Contribution Limits
- How Solo 401(k) Contributions Work: Employee vs Employer
- How to Calculate Your Solo 401(k) Maximum
- Catch-Up Contributions for Age 50 and Over
- Solo 401(k) vs SEP IRA vs SIMPLE IRA
- Solo 401(k) Rules and Deadlines
- Solo 401(k) FAQs
Solo 401(k) Contribution Rules
The IRS one-participant 401(k) plans page confirms who can open one, and IRS Publication 560 sets out the calculation in full.
Solo 401(k) plans are available to sole proprietors, partnerships, and corporations. In this guide and in the calculator above, we use 2026 limits of $24,500 for employee elective deferrals and $72,000 for the total annual cap. The employee piece always uses the plan year in which the contribution is made, not the year the return is filed. At a $100,000 income, for example, the calculator returns a maximum of $43,087.05 for a 45-year-old sole proprietor.
Every plan takes two contribution types, and the rules are straightforward:
- Any business with no employees other than a spouse can open a solo 401(k).
- The IRS permits one participant, and that employee can be the owner.
- The employee contribution is $24,500 for 2026.
- The employer contribution is limited to 25% of compensation for a corporation or 20% of net adjusted self-employment income for a sole proprietor.
The 2026 limits are:
2026 Solo 401(k) Contribution Limits
A solo 401(k) offers two contribution types that come with separate limits, but the combined total is capped at $72,000 for 2026. These limits apply to each plan, so if you have solo 401(k) plans through two unrelated businesses, each plan takes its own limits.
| Limit | Amount (2026) |
|---|---|
| Employee elective deferral | $24,500 |
| Total overall limit | $72,000 |
| Extra catch-up at age 50+ | $8,000 |
| Enhanced catch-up at ages 60–63 | $11,250 |
| Compensation cap | $360,000 |
| Age-50 catch-up | $8,000 |
The $24,500 elective deferral is the salary deferral limit, and it is also the standard salary deferral limit for 401(k) plans: it applies whether you only work for yourself or also have another job. An employee who contributes to another company plan will have their total salary deferrals across plans restricted to $24,500, including their solo 401(k) contribution.
The plan allows contributions from both the business and the owner, but an owner is not simply a business owner, the income has to be earned from self-employment itself.
How Solo 401(k) Contributions Work: Employee vs Employer
Employee contributions are the most powerful of the two. The plan permits salary deferrals subject to the $24,500 limit, and the compensation is based on the business income that the self-employed person earns. Most people also contribute a much higher percentage of their pay to the account, and earned income is an important planning tool: take a lower business income year and the employee contribution can fall.
| Contribution type | Who pays it | How it works |
|---|---|---|
| Employee elective deferral | The business owner | Up to $24,500 in 2026, plus catch-up if 50+ |
| Employer profit-sharing | The business | Up to 25% of compensation for corporations, 20% of net adjusted self-employment income for sole proprietors |
| Catch-up contribution | The business owner | Extra $8,000 per year at age 50 or older (2026) |
| Overall total | Both | Capped at $72,000 in 2026 |
The employer contribution is the other piece. Once you know the maximum total ($72,000 for 2026), you work out how much they can contribute and how to reach the limit.
- Sole proprietor — the employer contribution is capped at 20% of net adjusted self-employment income.
- S corporation — the employer contribution is capped at 25% of W-2 wages.
The practical rule is simple: employee contributions go up to $24,500, and the employer contribution tops up the plan to a maximum of $72,000.
How to Calculate Your Solo 401(k) Maximum
There are two simple formulas for the 2026 solo 401k maximum.
- Sole proprietor: Total contribution = $24,500 + (20% × net adjusted self-employment income)
- S corp: Total contribution = $24,500 + (25% × W-2 wages)
The calculator handles the detail, but the mechanics are simple enough to check by hand.
A sole proprietor works out their contributions using adjusted net self-employment income after halving the self-employment tax that would otherwise be due. Annual employer contributions in 2026 are capped at 20% of this net adjusted income, coming to $18,587.05 on $100,000 of income.
An S corp owner uses a simpler route, taking 25% of their W-2 wages and adding the $24,500 elective deferral, and the total is capped at $72,000.
Worked Example: A Sole Proprietor Earning $100,000
For a $100,000 income, the calculator returns the $43,087.05 maximum for a 45-year-old sole proprietor, broken down as:
| Component | Calculation | Amount |
|---|---|---|
| Employee deferral | Fixed | $24,500.00 |
| Employer profit-sharing | 20% × $92,935.24 | $18,587.05 |
| Catch-up contribution | Age 45, so none | $0.00 |
| Total contribution | Sum | $43,087.05 |
| Total contribution limit | Capped | $72,000.00 |
The total is $43,087.05.
Worked Example: An S Corp Owner With $100,000 in W-2 Wages
For an S corporation owner whose only income is W-2 wages, the results are:
| Component | Calculation | Amount |
|---|---|---|
| Employee elective deferral | Fixed | $24,500.00 |
| Employer profit-sharing | 25% × $100,000 | $25,000.00 |
| Catch-up contribution | Age 45, so none | $0.00 |
| Total contribution | Sum | $49,500.00 |
| Total as a percentage of wages | — | 49.5% |
The total here is $49,500 for 2026 once employer profit-sharing and employee deferral are combined.
Catch-Up Contributions for Age 50 and Over
The age-50 catch-up allows account holders aged 50 and over to contribute an extra $8,000 a year for 2026, and those aged 60 to 63 who are still in employment can use the enhanced catch-up of $11,250. The catch-up contributions are added on top of the other limits and are not subject to the $72,000 overall cap.
| Age group | Extra catch-up contribution |
|---|---|
| Under age 50 | $0.00 |
| Age 50 to 59 | $8,000.00 |
| Age 60 to 63 | $11,250.00 |
| Age 64 and older | $8,000.00 |
The IRS announces each year’s limits, so checking the current rules before filing keeps figures correct.
Solo 401(k) vs SEP IRA vs SIMPLE IRA
A solo 401(k) gives the highest contributions for most owner-operators, because the plan combines the employee salary deferral and the employer profit-sharing contribution. A SEP IRA only permits employer contributions and a SIMPLE IRA caps employee contributions at a far lower level. A solo 401(k) also permits a loan, while a SEP IRA and SIMPLE IRA do not allow the owner a loan.
| Plan | 2026 contribution cap | Loans | Roth option |
|---|---|---|---|
| Solo 401(k) | $72,000 | Yes | Yes |
| SEP IRA | $72,000 | No | No |
| SIMPLE IRA | $16,500 | No | No (SIMPLE Roth exists) |
Solo 401(k) Rules and Deadlines
A solo 401(k) offers some of the most flexible terms of any retirement plan, as well as clearer deadlines than SEP IRAs and SIMPLE IRAs:
The IRS places deadlines on solo 401(k) plans:
- Open the account by 31 December for the year you plan to do the contributions.
- Plan your contributions and have them made by 15 April of the following year, or by the later tax-filing deadline if extended.
One practical point: contributions should be deposited in the plan in the year they are due.
Solo 401(k) FAQs
Can I contribute to a solo 401(k) and an IRA?
Yes, you can contribute to both a solo 401(k) and an IRA, but your IRA contribution limit is the same $7,000 (or $8,000 from age 50) regardless.
What is the solo 401(k) contribution limit for 2026?
The 2026 employee elective deferral limit is $24,500, with the total annual plan limit set at $72,000.
Can I take a loan from my solo 401(k)?
Yes, you can take a loan from your solo 401(k), subject to the $50,000 or 50% of your balance limit, whichever is lower.
Who is eligible for a solo 401(k)?
Any business owner whose only employees are the owner and spouse can set up a solo 401(k). If the business has other employees, the business owner has to set up a standard 401(k) plan instead.
Can my spouse participate in a solo 401(k)?
Yes, spouses may participate in a solo 401(k) and make employee and employer contributions, but their participation must comply with the overall plan limits.
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