2026 Solo 401(k) Contribution Limits for Side Hustlers

Solo 401(k) Contribution Limits in 2026: How Side Hustlers Calculate Employee and Employer Contributions

A Solo 401(k) can let a self-employed person contribute as both an employee and an employer. That two-part structure creates a larger potential contribution than an employee deferral alone—but it also makes the calculation easy to misunderstand.

For 2026, the employee elective-deferral limit is $24,500, while the combined employee-and-employer limit is $72,000 before catch-up contributions. Your actual maximum may be lower because it depends on your business structure, compensation, contributions to other workplace plans, and the features included in your Solo 401(k) document.

This guide explains the 2026 Solo 401(k) contribution limits and walks through practical calculations for sole proprietors and S-corporation owners. The examples are estimates for educational purposes, not individualized tax or financial advice.

2026 Solo 401(k) Contribution Limits at a Glance

Contribution category	2026 limit
Employee elective deferral	$24,500
Combined employee and employer contributions	$72,000 before catch-up contributions
Standard catch-up for eligible participants age 50 or older	$8,000
Higher catch-up for eligible participants ages 60 through 63	$11,250, if permitted by the plan
Maximum with the standard catch-up	$80,000
Maximum with the ages 60–63 catch-up	$83,250
Compensation considered for plan calculations	Up to $360,000

These figures are ceilings, not automatic contribution amounts. Employee deferrals generally cannot exceed the participant’s eligible compensation. Employer contributions are also limited by compensation or adjusted self-employment earnings.

A Solo 401(k) is generally intended for a business with no eligible common-law employees other than the owner and, when applicable, the owner’s spouse. Businesses with employees should review eligibility and coverage rules before treating a plan as owner-only.

How the Two-Part Solo 401(k) Contribution Works

A Solo 401(k) uses the same basic contribution rules as other 401(k) plans. The distinguishing feature is that the business owner participates in two capacities.

Employee elective deferrals

As an employee, the owner can defer up to $24,500 for 2026, limited to available eligible compensation. Depending on the plan document, the contribution may be made as a traditional pre-tax deferral, a designated Roth contribution, or a combination of the two.

Traditional and Roth deferrals share the same $24,500 limit. Choosing Roth treatment does not create an additional employee-deferral allowance.

The employee limit also follows the individual across 401(k), 403(b), and certain other salary-deferral arrangements. Someone who contributes $18,000 to a workplace 401(k) during 2026 would generally have only $6,500 of the $24,500 employee-deferral limit left for a Solo 401(k).

Employer contributions

As the employer, the owner’s business may make a profit-sharing or nonelective contribution. The calculation depends on how the business is taxed:

An S-corporation generally calculates the contribution using the owner’s W-2 wages.
A sole proprietor or single-member LLC taxed as a sole proprietorship generally uses adjusted net earnings from self-employment.
A partnership or LLC taxed as a partnership uses a partner-specific calculation based on eligible earned income.

The employee and employer amounts stack, but regular annual additions generally cannot exceed the lower of $72,000 or the applicable compensation-based limit. Catch-up contributions for eligible participants are permitted above the $72,000 ceiling.

How to Calculate the Employer Contribution

Sole proprietors and single-member LLCs

A sole proprietor cannot simply multiply gross revenue—or even Schedule C net profit—by 25%. The calculation generally begins with net profit and adjusts it for the deductible portion of self-employment tax and the owner’s retirement-plan contribution.

For a plan with a stated 25% employer contribution rate, the corresponding self-employed rate is generally 20% because the contribution itself reduces the compensation used in the calculation. A practical estimate is:

Start with Schedule C net profit.
Calculate net earnings subject to self-employment tax, generally using 92.35% of net profit.
Estimate Social Security and Medicare taxes, taking account of wages from another job and the applicable Social Security wage base.
Subtract the deductible one-half of self-employment tax from net profit.
Apply the effective self-employed plan contribution rate, commonly 20% for a plan using a 25% corporate contribution rate.
Apply the $72,000 combined limit and other compensation restrictions.

Self-employment tax can become more complicated when the owner also has W-2 wages, exceeds the Social Security wage base, or owes Additional Medicare Tax. IRS worksheets or tax software should be used for the final amount.

S-corporation owners

An S-corporation generally may contribute up to 25% of the shareholder-employee’s eligible W-2 compensation, subject to the plan terms and overall limit. Shareholder distributions do not count as compensation for this calculation.

For example, an owner receiving $100,000 of W-2 wages and $80,000 of distributions generally calculates the employer contribution from the $100,000 salary—not the combined $180,000 of cash received.

For 2026, no more than $360,000 of compensation may be considered for qualified-plan contribution calculations. However, the $72,000 annual-additions ceiling will often become binding before the compensation limit does.

Worked Solo 401(k) Examples for Side Hustlers

Example 1: Sole proprietor with $150,000 of net profit

Assume an owner is under age 50, has no W-2 job, has $150,000 of Schedule C net profit, and makes the full $24,500 employee deferral. For illustration, assume all relevant net earnings remain subject to the regular Social Security and Medicare components of self-employment tax.

Estimated net earnings for self-employment tax: $150,000 × 92.35% = $138,525.
Estimated self-employment tax: $138,525 × 15.3% = approximately $21,194.
Deductible one-half of estimated self-employment tax: approximately $10,597.
Adjusted earnings estimate: $150,000 − $10,597 = approximately $139,403.
Estimated employer contribution: $139,403 × 20% = approximately $27,881.
Employee deferral: $24,500.
Estimated total contribution: $27,881 + $24,500 = approximately $52,381.

This example does not reach the $72,000 maximum because the employer contribution is constrained by adjusted business earnings. The exact result may differ when the return is prepared, particularly if the owner has wages from another job or other items affecting self-employment tax.

Example 2: S-corporation owner with salary and distributions

Assume an owner under age 50 receives a $100,000 W-2 salary plus $80,000 of S-corporation distributions. The plan provides for a 25% employer contribution.

Employee deferral: $24,500.
Employer contribution: 25% of $100,000 = $25,000.
Estimated combined contribution: $49,500.

The $80,000 distribution does not increase the employer contribution. If the same owner received only $60,000 of W-2 wages, the 25% employer contribution would fall to $15,000, producing a combined contribution of $39,500.

Salary decisions involve payroll taxes, reasonable-compensation requirements, cash flow, and retirement-plan goals. Retirement contribution capacity should not be used as the only factor in setting an S-corporation owner’s wages.

Example 3: When the $72,000 cap applies

Assume an S-corporation owner under age 50 earns $200,000 in W-2 wages and contributes $24,500 as an employee. A 25% employer contribution would initially calculate to $50,000.

Employee deferral: $24,500.
Percentage-based employer amount: $50,000.
Unadjusted total: $74,500.
Maximum regular annual additions: $72,000.
Maximum employer contribution after applying the cap: $47,500.

The percentage formula does not override the $72,000 combined limit. The employer amount must be reduced by $2,500 in this example.

Catch-Up Contributions and the 2026 Roth Requirement

A participant who is age 50 or older by the end of 2026 may generally make an $8,000 catch-up contribution if the plan permits catch-ups. This can raise the total to as much as $80,000.

Participants who are ages 60 through 63 by the end of the year may qualify for the higher SECURE 2.0 catch-up of $11,250. If the plan supports this provision and the participant otherwise qualifies, the potential total becomes $83,250. The $11,250 amount replaces the standard $8,000 catch-up; it is not added to it.

Starting in 2026, certain higher-paid participants must make catch-up contributions as designated Roth contributions. The rule generally applies when the participant had more than $150,000 of prior-year FICA wages from the employer sponsoring the plan.

This wage-based rule requires careful administration:

It looks to prior-year FICA wages, not total household income.
Schedule C profit by itself is not FICA wages.
An S-corporation owner’s wages from the corporation may trigger the requirement.
The plan must have the necessary Roth provisions and administrative procedures.
Age eligibility and the plan’s adoption terms should be confirmed before relying on either catch-up limit.

Plan providers may need time to classify contributions correctly. Owners affected by the Roth requirement should confirm procedures before sending a year-end contribution.

Common Solo 401(k) Limit Mistakes to Avoid

Treating the $24,500 employee limit as available in every plan. It is a per-person limit across the plans in which that person makes elective deferrals, not a separate allowance for each job.
Using gross business revenue. Contributions are based on eligible compensation or adjusted earned income, not top-line sales.
Counting S-corporation distributions as compensation. Employer contributions for a shareholder-employee are generally based on W-2 wages.
Ignoring the self-employment-tax adjustment. Sole proprietors generally must reduce net profit by the deductible portion of self-employment tax before completing the contribution calculation.
Assuming every plan permits Roth contributions. Roth deferrals, voluntary after-tax contributions, and Roth conversions are distinct features and must be authorized by the plan.
Assuming the higher ages 60–63 catch-up is automatic. The participant and plan must both qualify.
Misapplying the spouse rule. Each spouse has an individual employee-deferral limit. However, a spouse participating in both a workplace plan and the family business’s Solo 401(k) must coordinate that spouse’s own deferrals across plans.
Overfunding before final compensation is known. Estimated income can decline, reducing the allowable employer contribution.
Failing to correct an excess deferral promptly. Excess contributions can create additional reporting and tax complications. Contact the plan administrator and tax professional as soon as an error is discovered.

What to Do Next Before Making 2026 Contributions

Confirm eligibility. Verify that the business has no eligible employees other than the owner and possibly the owner’s spouse.
Identify the tax structure. Determine whether the calculation uses Schedule C profit, partnership earned income, or S-corporation W-2 wages.
Total other employee deferrals. Include 2026 elective deferrals made through another employer’s plan.
Review the plan document. Check whether it permits traditional deferrals, Roth deferrals, catch-ups, voluntary after-tax contributions, and any desired conversion features.
Calculate the two portions separately. Estimate the employee deferral first, then calculate the employer contribution from eligible compensation.
Apply the combined limit. Regular employee and employer additions generally cannot exceed $72,000, while eligible catch-up contributions sit above that amount.
Verify deadlines. Election and funding deadlines can differ by contribution type, entity structure, plan terms, and tax-filing extensions.
Reconcile the estimate before filing. Use final payroll records, business income, and self-employment-tax figures rather than relying only on an early projection.

The central calculation is straightforward once the correct compensation figure is identified: employee deferrals and employer contributions are separate components, but they share the $72,000 regular annual limit. The difficult part is determining eligible compensation correctly and coordinating the Solo 401(k) with other plans.

Before funding a large 2026 contribution, confirm the result with the plan provider, current IRS guidance, or a tax professional familiar with the business’s entity structure.