Solo 401(k) Contribution Calculator
Calculate your maximum 2026 Solo 401(k) contribution as a self-employed worker. Combines the $23,500 employee elective deferral with the 25% employer profit-sharing contribution, capped at a $70,000 total (or $77,500 with age-50 catch-up).
What Is a Solo 401(k)?
A Solo 401(k) is a retirement plan designed for self-employed individuals and owner-only businesses with no full-time employees other than a spouse. Because you play both roles — employee and employer — you can contribute in two ways, which lets Solo 401(k) savers shelter far more income than a traditional IRA or SEP-IRA at the same earnings level. This calculator uses the 2026 IRS limits to show your exact maximum contribution.
2026 Contribution Limits
For 2026, the employee elective deferral limit is $23,500 (or $31,000 if you are age 50 or older, including the $7,500 catch-up). The employer profit-sharing piece is up to 25% of net self-employment earnings. The combined annual additions limit is $70,000, or $77,500 with catch-up. "Net self-employment earnings" means net Schedule C profit minus half of self-employment tax — the calculator handles that adjustment automatically.
Employee vs Employer Contributions
The employee portion is a flat-dollar deferral you can make up to the elective limit regardless of income. The employer portion is a percentage of earned income — effectively 20% of net self-employment earnings after the SE tax adjustment, which equals 25% of the post-contribution base. Maxing both is how Solo 401(k) holders routinely shelter $60,000+ in a single year. Roth Solo 401(k) variants let you designate the employee portion as after-tax for tax-free growth.
Solo 401(k) vs SEP-IRA
At lower incomes, Solo 401(k) lets you save much more because the $23,500 employee deferral is not tied to income. A SEP-IRA only allows the 25% employer piece, so at $50,000 net SE income the SEP caps near $9,300 while the Solo 401(k) allows roughly $32,800. At very high incomes both plans converge on the $70,000 cap. Solo 401(k)s also allow loans and Roth treatment — SEP-IRAs do not.
Frequently Asked Questions
What is the 2026 Solo 401(k) contribution limit?
For 2026, the total annual additions limit is $70,000 (or $77,500 if age 50+). This combines the $23,500 employee elective deferral with up to 25% of net self-employment earnings as the employer profit-sharing contribution.
How is the employer contribution calculated for Schedule C filers?
Schedule C filers contribute up to 20% of net self-employment earnings (net profit minus half of self-employment tax). The published rate is 25% but it is applied to the post-contribution base, which works out to 20% of the pre-contribution base.
Can my spouse also contribute if they work in the business?
Yes. If your spouse earns income from the business, they can participate in the same Solo 401(k) and contribute their own employee deferral and employer share, effectively doubling the household retirement savings.
What if I have a day job with a 401(k)?
The $23,500 employee deferral is shared across all 401(k) plans you participate in — including your W-2 employer plan. However, the $70,000 total additions limit is per plan, so you can still receive employer contributions in both plans up to $70,000 each.
Is a Solo 401(k) better than a SEP-IRA?
For most self-employed savers, yes. The Solo 401(k) allows both employee deferrals and employer contributions, supports Roth, and allows loans. A SEP-IRA only allows the employer 25% piece, meaning at moderate income levels you can contribute 2-3x more via Solo 401(k).
When is the Solo 401(k) contribution deadline?
The plan must be established by December 31 of the tax year. Employee deferrals must be elected by year-end, but actual funding (both employee and employer) can happen up to the tax filing deadline including extensions (typically October 15).