Solo 401k Contribution Calculator (2026)

Data Sources & Methodology

Our Solo 401k Contribution Calculator uses 2026 IRS retirement plan limits. All data is verified as of May 2026.

• Employee Deferral Limit: $24,500 base + catch-up provisions from IRS 401k Contribution Limits.
• SECURE 2.0 Catch-Up: $11,250 super catch-up for ages 60–63 from IRS Catch-Up Contributions.
• Employer Contribution: 25% of net SE income from IRS One-Participant 401k Plans.

How We Calculate: Employee deferral is capped at the age-adjusted limit. Employer contribution = net SE income × 0.9235 × 25%, capped at $47,500. Total is capped at $72,000. Tax savings = total contribution × (federal bracket + state rate). SE tax savings = employee deferral × 0.9235 × 15.3%. Net cost = total contribution − total tax saved.

How to Use the Solo 401k Contribution Calculator

Using our free Solo 401k Contribution Calculator is straightforward. Enter your net self-employment income (after business expenses but before taxes), select your age group to apply the correct IRS contribution limits, and choose how much you want to contribute as an employee. The calculator instantly shows your maximum allowable employee and employer contributions, total tax savings across federal, state, and self-employment taxes, and the net after-tax cost of your retirement contribution.

Formula & Calculation Breakdown

The Solo 401k contribution calculation involves three main components:

Employee Salary Deferral: For 2026, the base limit is $24,500 for those under 50. Regular catch-up contributions ($8,000 extra) apply for ages 50–59 and 64+, bringing the limit to $32,500. The SECURE 2.0 super catch-up ($11,250 extra) applies for ages 60–63, raising the limit to $35,750.

Employer Profit-Sharing: The employer contribution is 25% of your net SE income after the SE tax deduction. To calculate: Net SE Income × 0.9235 × 0.25. The employer portion is capped at $47,500 for 2026.

Total Limit: Combined employee and employer contributions cannot exceed $72,000 for 2026 (or 100% of net SE income, whichever is less).

Example 1: Freelance Designer (Under 50)

Sarah, a freelance graphic designer, earns $80,000 net SE income. She is 34 years old. Her employee limit is $24,500. She chooses to contribute the full $24,500. Her employer contribution is: $80,000 × 0.9235 × 0.25 = $18,470. Total contribution: $24,500 + $18,470 = $42,970 (under the $72,000 cap). At a 22% federal bracket and 5% state rate, she saves $11,602 in taxes, making her net cost just $30,220.

Example 2: Consultant (Age 62, Super Catch-Up)

Michael, a management consultant aged 62, earns $200,000 net SE income. His super catch-up employee limit is $35,750. He contributes the max $35,750. Employer contribution: $200,000 × 0.9235 × 0.25 = $46,175. Total: $35,750 + $46,175 = $81,925, but this exceeds the $72,000 total cap, so the total is limited to $72,000. At 32% federal and 5% state, his tax savings are $25,900, net cost $44,100.

Example 3: Part-Time Etsy Seller (Age 55, Lower Income)

Maria runs an Etsy shop earning $30,000 net SE income. She is 55. Employee limit is $32,500, but she can only contribute up to her income. She contributes $20,000. Employer contribution: $30,000 × 0.9235 × 0.25 = $6,926. Total: $20,000 + $6,926 = $26,926. At 12% federal and 0% state (Texas), her tax savings are $5,636, making the net cost just $21,290 to save $26,926.

Traditional vs Roth Solo 401k: Which is Right for You in 2026?

Choosing between Traditional and Roth Solo 401k contributions depends on your current versus expected future tax rate. Traditional contributions provide an immediate tax deduction at your marginal rate today, which is ideal if you're in a higher bracket now and expect to withdraw at a lower rate in retirement.

Roth Solo 401k contributions don't reduce your current tax bill but offer tax-free growth and withdrawals. This makes Roth particularly attractive for younger self-employed individuals who are in lower tax brackets today and expect their income to grow significantly.

Real-Life Scenarios: 3 User Types

Case 1 — The Full-Time Freelancer: Jake, 41, earns $120,000 as a freelance software developer. He contributes $24,500 as employee and receives the full employer match of $27,705. Total: $51,205. At 24% federal and 4.95% Illinois state tax, his total tax savings are $16,637.

Case 2 — The Side Hustler with a Full-Time Job: Priya, 36, earns $90,000 at her W-2 job and $35,000 from her Etsy shop. At her W-2 job, she defers $12,000 to her employer 401k. She can only defer $12,500 more to her Solo 401k (combined $24,500 limit).

Case 3 — The Near-Retiree: Robert, 61, earns $95,000 from his consulting practice. His super catch-up limit is $35,750. He contributes $35,750. Employer contribution: $21,933. Total: $56,683. At 22% federal and 3.07% Pennsylvania state tax, his tax savings are $14,735.

8 Tips to Maximize Your Solo 401k Savings in 2026

1. Max out employee deferrals first. The employee portion gives you the most flexibility and reduces both income tax and self-employment tax.

2. Coordinate with other retirement plans. If you have a W-2 job with a 401k, remember the combined employee deferral limit applies across all plans.

3. Use the super catch-up if you're 60–63. The SECURE 2.0 $11,250 super catch-up is the highest catch-up limit ever for this age group.

4. Make employer contributions after year-end. You have until your tax filing deadline to make employer profit-sharing contributions.

5. Consider Roth contributions for tax-free growth. If you're in a lower bracket now than you expect in retirement, Roth contributions lock in today's rate.

6. Don't forget state tax savings. In California (9.3%), the state tax savings alone on a $50,000 contribution is $4,650.

7. Open the plan before December 31. You must establish the plan by December 31 of the tax year.

8. Roll over old 401k balances. Consolidate old 401k accounts from previous employers into your Solo 401k.

Common Mistakes to Avoid

Over-contributing above the limit. Exceeding the combined $72,000 limit triggers a 6% excise tax on the excess each year until corrected.

Forgetting the employer contribution cap. Many solo entrepreneurs max out employee deferrals but forget they're also entitled to the 25% employer contribution.

Missing the SE tax deduction on employer contributions. Only employee deferrals reduce self-employment tax.

Not updating beneficiary designations. Solo 401k plans require proper beneficiary designations.

Ignoring required minimum distributions (RMDs). Once you turn 73, RMDs apply to Traditional Solo 401k balances.

Failing to file Form 5500-EZ. If your Solo 401k balance exceeds $250,000 at year-end, you must file Form 5500-EZ annually.

Frequently Asked Questions

Q: What is the Solo 401k contribution limit for 2026?
A: The total limit is $72,000. The employee deferral limit ranges from $24,500 (under 50) to $35,750 (ages 60–63 with super catch-up).

Q: Who qualifies to open a Solo 401k?
A: Self-employed individuals with no full-time W-2 employees other than a spouse.

Q: What is the SECURE 2.0 super catch-up for age 60–63?
A: It allows an additional $11,250 in employee deferrals beyond the standard $24,500 limit.

Q: Can I have both a Solo 401k and a regular employer 401k?
A: Yes, but the combined employee deferral limit applies across all plans.

Q: How is the employer contribution calculated?
A: Take your net SE income, multiply by 0.9235, then multiply by 25%.

Q: Traditional vs Roth Solo 401k — which reduces taxes more now?
A: Traditional reduces current taxes. Roth provides tax-free withdrawals in retirement.

Q: What is the deadline to open and contribute for 2026?
A: Open by December 31, 2026. Employee deferrals by April 15, 2027 (or October 15 with extension).

Q: Does Solo 401k reduce self-employment tax?
A: Only employee salary deferrals reduce SE tax. Employer profit-sharing contributions do not.