Solo 401(k) Contribution Calculator 2026
Estimate the employee and employer contribution pieces of a 2026 solo 401(k), including the updated IRS elective deferral, catch-up, and annual additions limits.
Last updated: April 3, 2026
Calculator
This tool is built for one-participant planning. Self-employed mode uses a simplified earned-income adjustment and should be treated as a planning estimate rather than a filing worksheet.
Official 2026 solo 401(k) values used
- Employee elective deferral limit: $24,500
- Standard catch-up for age 50 and over: $8,000
- Higher catch-up for ages 60 to 63: $11,250
- Defined contribution annual additions limit, excluding catch-up: $72,000
- Compensation cap used for employer contributions: $360,000
How to think about the result
A solo 401(k) usually has two moving parts: the employee elective deferral and the employer contribution. The IRS annual additions cap applies to the combined non-catch-up amount. Catch-up contributions sit on top of that limit when age rules allow them.
For self-employed owners, the employer contribution math is not exactly the same as a flat 25% of net profit. That is why the self-employed mode here is labeled as a planning estimate.
Related pages
How to use the result
Start by treating the employee elective deferral and employer contribution as separate buckets. If the employee piece already uses most of the annual additions limit, the employer side may be smaller than you first expect. That is normal and is one of the most common solo 401(k) planning surprises.
In self-employed mode, focus on the direction of the estimate first. If the result is close to a limit that affects a real funding decision, it is worth checking the final number with tax software or a CPA before you actually make the contribution.
Examples
W-2 owner example
If an owner has $120,000 of W-2 compensation, elects the full $24,500 employee deferral, and uses a 25% employer rate, the employer contribution can still be substantial. The calculator shows how much room remains under the annual additions cap.
Self-employed example
If a self-employed owner enters $120,000 of net income, the employer side will usually come out lower than a flat 25% of that number because the planning formula uses adjusted earned income rather than raw profit.
Age-61 example
For someone age 61, the larger catch-up amount can increase the total contribution materially. That is why the calculator asks for age directly instead of assuming one catch-up number for everyone over 50.
Common mistakes
- Treating the employer piece like a simple wage-style percentage in self-employed cases.
- Forgetting that the $72,000 annual additions cap is separate from catch-up contributions.
- Assuming a solo 401(k) works exactly like a SEP IRA.
- Using the right formula on the wrong income base.
FAQ
Does this tool include Roth solo 401(k) planning?
No. It focuses on contribution amounts, not whether the employee deferral is Traditional or Roth.
Can I use this if I have employees?
Not really. This page is built around one-participant planning.