When is the deadline to open a Solo 401(k)?

For a 2026 contribution, the plan must generally be established by December 31, 2026.

Can my spouse participate?

Yes, if they work for the business, they can have their own employee and employer contributions within the same plan, effectively doubling your household savings.

Solo 401(k) & Mega Backdoor Calculator

Plan your 2026 self-employed contributions and find out how much you can squirrel away in a Roth.

Calculate Your Results

Adjust the values to see how your numbers change

What is a Solo 401(k)?

A Solo 401(k) (also known as a Self-Employed 401k) is a powerful retirement plan for business owners with no employees (except a spouse). It offers some of the highest contribution limits in the US tax code.

The plan is unique because you wear two hats: the Employee (who can defer up to $24,000) and the Employer (who can contribute up to 25% of compensation). Total contributions for 2026 can reach $71,000 (plus catch-up).

How to Use This Calculator

Business Net Income - Determine your expected annual profit (Revenues minus Expenses).
Check Age - If you are 50 or older, you get an extra $7,500 in catch-up space.
Other 401(k)s - If you have a W-2 job, those contributions count toward your $24,000 employee limit.
Optimize for Roth - Check the Mega Backdoor space to see how much you can put into tax-free Roth accounts.

Calculation Formula & Example

The Formula

Max Total = Employee Deferral + Employer (20-25% of Net) + After-Tax Voluntary

Where:

Employee = $24,000 max for 2026 (+ $7,500 if age 50+)
Employer = Generally 20% of net income for sole proprietors
Total Cap = $71,000 for 2026

Example Calculation

If you earn $150,000 net, you can put $24,000 as an employee and ~$30,000 as an employer match. The remaining ~$17,000 can be contributed as after-tax 'Mega Backdoor' if your plan supports it.

Benefits of Using This Calculator

Highest Savings Limits - Much higher than a SEP IRA or SIMPLE IRA at similar income levels.
Roth Option - Unlike a SEP IRA, your employee portion can be 100% Roth.
Participant Loans - Solo 401(k)s often allow you to borrow against your balance if needed.

Calculator Use Cases

Freelancers/Consultants

The gold standard for high-earning independent workers.

Side Hustlers

If you have a W-2 job but also a side business, you can use a Solo 401(k) for the side income.

Frequently Asked Questions

Related Financial Tools

Backdoor Roth IRA

Combine this with your Solo 401(k) for ultimate tax-free growth.

Use Calculator

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