Free Solo 401k Calculator (2026)

A desk setup with a notebook labeled '401k', a pen, cash, and a calculator representing financial planning.

The Solo 401k (also called an Individual 401k or Self-Employed 401k) is the most powerful retirement plan available to self-employed workers with no full-time employees. For 2026, you can contribute up to $70,000 if you are under 50 — or $77,500 if you are 50 or older — by combining employee deferrals and employer profit-sharing contributions. Use our free solo 401k calculator to find your exact maximum contribution, compare it to a SEP IRA, and see your estimated tax savings.

free solo 401k calculator

Free Solo 401k Calculator

Calculate your 2026 maximum Solo 401k contribution — employee + employer portions


Gross business income minus business expenses, before SE tax deduction

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SECURE 2.0 Act allows an enhanced catch-up for ages 60–63 starting in 2025


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The employer profit-sharing portion is always pre-tax regardless of this choice

How This Free Solo 401k Calculator Works

Step 1: Choose Your Business Structure

The Solo 401k contribution formula differs depending on whether you are a sole proprietor filing Schedule C or an S-corp owner paying yourself W-2 wages. This free solo 401k calculator handles both structures and automatically applies the correct IRS formulas for each.

Step 2: Enter Your Income

For sole proprietors, enter your net Schedule C profit — gross business revenue minus all business expenses, before the self-employment tax deduction. For S-corp owners, enter your W-2 salary paid by the corporation. The calculator applies the required SE tax adjustments automatically for sole proprietors.

Step 3: Select Your Age

Your age determines whether you qualify for catch-up contributions. Workers age 50–59 or 64+ can add $7,500, while workers age 60–63 can add an enhanced $11,250 under the SECURE 2.0 Act. The free solo 401k calculator factors these amounts in automatically.

Step 4: Review Your Complete Breakdown

Your results show the employee deferral portion, employer profit-sharing portion, catch-up contribution (if applicable), total maximum contribution, a side-by-side SEP IRA comparison, estimated tax savings, and a 10-year compound growth projection.

Frequently Asked Questions

What is the 2026 Solo 401k contribution limit?

For 2026, the total Solo 401k limit is $70,000 for those under 50, comprised of a $23,500 employee deferral plus up to 25% of compensation as employer profit-sharing (capped at $46,500). Workers 50–59 or 64+ can add $7,500 in catch-up contributions for a total of $77,500. Workers age 60–63 can add $11,250 for a total of $81,250. Use our free solo 401k calculator to find your exact number based on your income.

What is the difference between the employee and employer contribution?

The employee deferral ($23,500 for 2026) is your personal contribution as a worker — you can contribute this amount regardless of income level, as long as you have at least $23,500 in net self-employment income. The employer profit-sharing portion (up to 25% of compensation) is the business’s contribution on your behalf. Together they cannot exceed the annual addition limit of $70,000 (before catch-up).

How is the employer portion calculated for sole proprietors?

For sole proprietors, the employer profit-sharing contribution is calculated using the same adjusted formula as a SEP IRA: net Schedule C profit × 92.35% to find SE earnings, then subtract the deductible half of SE tax from net profit, then multiply the result by 20% (equivalent to 25% of the adjusted amount). This is why the effective employer rate works out to approximately 18.587% of net income rather than a full 25%.

Is a Solo 401k better than a SEP IRA?

For most self-employed individuals earning under approximately $200,000, the Solo 401k allows significantly larger contributions than a SEP IRA because of the additional $23,500 employee deferral. At very high income levels ($350,000+), both plans approach the same $69,000–$70,000 ceiling. The Solo 401k also offers Roth contributions, participant loans, and catch-up contributions — none of which are available in a SEP IRA. The SEP IRA wins on simplicity and has no annual filing requirement. Try our free SEP IRA calculator for a direct comparison.

Can I have a Solo 401k and a SEP IRA?

Technically yes, but it rarely makes sense. The employer profit-sharing contributions across all plans share the same $69,000 annual additions limit, and the $23,500 employee deferral limit applies across all 401k plans you participate in. Most advisors recommend choosing one plan and maximizing it rather than splitting contributions.

What is the SECURE 2.0 enhanced catch-up?

The SECURE 2.0 Act of 2022 introduced an enhanced catch-up contribution for participants age 60–63, starting in 2025. Instead of the standard $7,500 catch-up, workers in this age range can contribute $11,250 as catch-up — raising the total possible Solo 401k contribution to $81,250 for 2026. This is the highest contribution available in any self-employed retirement plan.

Can I make Roth contributions to a Solo 401k?

Yes. The employee deferral portion ($23,500 plus any catch-up) can be designated as Roth, meaning you pay tax now but withdrawals in retirement are tax-free. The employer profit-sharing portion must always be pre-tax (Traditional). This flexibility is a major advantage of the Solo 401k over the SEP IRA, which has no Roth option.

When is the Solo 401k contribution deadline?

Employee deferrals must be made by December 31, 2026 for the 2026 tax year. Employer profit-sharing contributions can be made until your tax filing deadline, including extensions — as late as October 15, 2027 for sole proprietors or September 15, 2027 for S-corps.

Do I need to file anything with the IRS?

If your Solo 401k plan assets exceed $250,000 at the end of the year, you must file Form 5500-EZ with the IRS. This is a simple one-page form. Plans with less than $250,000 in assets have no filing requirement. This is one area where the SEP IRA has a slight edge — it never requires a Form 5500.

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Understanding the Solo 401k for Self-Employed Workers

The Solo 401k — formally known as the Individual 401k or One-Participant 401k — was designed to give self-employed individuals access to the same powerful retirement savings structure that large employers offer their workers. Before the Solo 401k became widely available through the Economic Growth and Tax Relief Reconciliation Act of 2001, self-employed workers were largely limited to SEP IRAs and SIMPLE IRAs, both of which have lower effective contribution limits at moderate income levels.

The key innovation of the Solo 401k is its dual contribution structure. As a self-employed person, you act as both the employee and the employer. As the employee, you can defer up to $23,500 of your earned income (2026) — this is the same deferral limit that applies to employees at Fortune 500 companies. As the employer, your business can contribute an additional profit-sharing amount of up to 25% of your compensation. Together, these two components allow total contributions far exceeding what a SEP IRA alone would permit at the same income level.

Why the Solo 401k Beats the SEP IRA at Lower Incomes

Consider a freelancer earning $50,000 in net Schedule C profit. Under a SEP IRA, the maximum contribution would be approximately $9,294 (using the IRS self-employed formula). Under a Solo 401k, that same freelancer could contribute $23,500 as an employee deferral plus approximately $9,294 as employer profit-sharing — for a total of $32,794. That is more than three times the SEP IRA limit at the same income level. This advantage narrows as income increases, and by approximately $350,000 in net income, both plans approach similar ceilings. But for the vast majority of self-employed workers earning between $30,000 and $200,000, the Solo 401k provides significantly more retirement savings capacity.

The SECURE 2.0 Enhanced Catch-Up Contribution

Beginning in 2025, the SECURE 2.0 Act introduced a higher catch-up contribution limit for retirement plan participants aged 60 through 63. Instead of the standard $7,500 catch-up (available to those 50+), workers in the 60–63 age window can contribute an additional $11,250. This brings the maximum possible Solo 401k contribution for a high-earning 62-year-old to $81,250 in 2026 — the highest contribution limit available in any self-employed retirement plan. Workers age 64 and older revert to the standard $7,500 catch-up. Use this free solo 401k calculator to see exactly how the enhanced catch-up affects your personal maximum.

Roth Solo 401k Contributions

Unlike the SEP IRA, the Solo 401k allows you to designate your employee deferral as a Roth contribution. Roth contributions are made with after-tax dollars — you pay income tax now, but qualified withdrawals in retirement are completely tax-free. This can be enormously valuable if you expect to be in a higher tax bracket in retirement, or if you want tax diversification across your retirement portfolio. The employer profit-sharing portion must always be contributed on a pre-tax (Traditional) basis, regardless of your election for the employee deferral.

Filing Requirements and Plan Administration

The Solo 401k does require slightly more administration than a SEP IRA. You must adopt a written plan document (most brokerages provide one free), and if your plan assets exceed $250,000 at year-end, you must file Form 5500-EZ annually with the IRS. This is a simple one-page form, but it is an important compliance requirement that SEP IRA holders do not face. Additionally, employee deferrals must be made by December 31 of the tax year, while employer contributions can be deferred until the tax filing deadline including extensions.

Who Qualifies for a Solo 401k?

To open and maintain a Solo 401k, you must have self-employment income and no full-time employees other than yourself (and your spouse, who can also participate). If you hire full-time employees — defined as anyone who works 1,000+ hours per year — you generally cannot maintain a Solo 401k and would need to establish a traditional 401k plan with broader eligibility. Part-time workers under the 1,000-hour threshold can typically be excluded. For detailed eligibility rules, see the IRS one-participant 401k plans guidance page.

The Solo 401k is widely considered the single best retirement plan available to self-employed individuals without employees. Its combination of high contribution limits, Roth flexibility, catch-up contributions, and loan provisions makes it the most versatile option in the self-employed retirement toolkit — and running a free solo 401k calculator before year-end ensures you capture every dollar of tax-deferred savings available to you.

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