Solo 401(k) Contribution Calculator

Choose the correct compensation input

For a sole proprietor, enter net business profit after business expenses, not gross revenue. The calculation first subtracts the deductible half of regular self-employment tax. Employer contributions then require the special self-employed computation rather than simply taking 25% of Schedule C profit.

For an incorporated owner receiving wages, enter compensation eligible under the plan. Shareholder distributions are not automatically eligible wages. Choose the business type carefully: the same $100,000 revenue figure can produce a very different limit depending on expenses, payroll, and entity structure.

For the wage-based calculation, the displayed employee and employer amounts are one allocation that maximizes the modeled total. Other allocations can reach the same total; the components are not separate maxima to add together.

Enter regular elective deferrals made to other plans and any catch-up amount already used. The employee deferral limit generally applies by person across relevant plans, not separately to every job. The IRS one-participant 401(k) guidance explains that coordination and the special self-employed calculation.

Continue with SEP IRA Contribution Calculator or Roth Conversion Calculator for the next calculation.

2026 limits used in this estimate

The IRS contribution-limit table lists a $24,500 regular elective-deferral limit and a $72,000 defined-contribution annual-additions limit for 2026, subject to compensation and other rules. Catch-up contributions are outside the ordinary annual-additions limit.

The regular age 50-or-older catch-up limit is $8,000. For participants who attain age 60, 61, 62, or 63 during 2026, the applicable higher limit is $11,250 instead of $8,000, when the plan permits it. These figures are maximum legal parameters, not a promise that a particular income level supports the maximum contribution.

Some 2026 catch-up contributions must be Roth based on prior-year wages with the sponsoring employer. The IRS catch-up guidance gives the 2026 threshold as more than $150,000 of those prior-year wages. Confirm plan handling; contribution capacity and current tax deductibility are different questions.

Example: $100,000 sole-proprietor profit

Assume an owner under 50 has $100,000 of net profit, no other wages, no other plan deferrals, and a plan allowing the maximum employer rate. Regular self-employment tax in this illustration is $14,129.55. The deductible half is $7,064.775 before display rounding, leaving adjusted earnings of $92,935.225.

The regular employee deferral is $24,500. The employer portion is 20% of adjusted earnings under the reduced self-employed rate, or $18,587.045. The total modeled contribution is $43,087.05 after display rounding.

This example assumes the plan's eligibility and timing requirements are met. It does not include catch-up, voluntary after-tax contributions, or contributions for another participant. The IRS Publication 560 worksheet supplies the self-employed deduction framework.

Why lower profit needs an extra limit

It is not always correct to add the full employee deferral to 20% of adjusted earnings. The worksheet also limits the employer amount in relation to earnings left after regular deferrals. At low profit, an owner may use the available compensation entirely for the employee contribution, leaving no deductible employer contribution under this model.

For example, at $10,000 net profit with no other wages or deferrals, adjusted earnings are about $9,293.52. A maximum-deferral scenario uses that amount for regular employee contributions and produces $0 employer contribution. Adding another 20% would overstate this scenario's result.

Use the result as a contribution estimate

Confirm the plan document, eligible compensation, contribution elections, deadlines, and other-plan coordination before funding. Businesses with eligible nonowner employees require more than an owner-only calculator. Related employers, multiple self-employed plans, and special compensation situations are outside this simplified model.

The retirement withdrawal calculator can help explore how savings might support future spending. The life insurance needs calculator addresses a separate household protection need; retirement contributions do not replace that analysis.

Frequently asked questions