# How much can I put in a solo 401(k)?

Works out the most a self-employed person can put into a solo 401(k) for 2026: elective deferrals, catch-up and the employer contribution, from net profit by the IRS worksheet for the self-employed.

- Page: https://www.acalculator.org/finance/solo-401k-calculator
- JSON spec: https://www.acalculator.org/finance/solo-401k-calculator.json
- Version: 623d05e402f5

## Default answer

Example with the default inputs (Net self-employment profit $100,000.00, Your age at the end of 2026 Under 50, Employer contribution rate 25%): With $100,000.00 of net profit, you can put up to $43,087.05 into a solo 401(k) for 2026.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| profit | Net self-employment profit | Your 2026 net profit from the business (Schedule C line 31), or your share of partnership self-employment earnings. |
| age | Your age at the end of 2026 | Catch-up contributions start at 50; ages 60 to 63 get a larger catch-up. |
| rate | Employer contribution rate | The plan’s employer (profit-sharing) rate, up to 25%. |
| other | Deferrals to other 401(k) plans (optional) | Elective deferrals you make in 2026 to another employer’s 401(k), 403(b) or similar plan; they share the limit. |
| w2 | Social Security wages from a job (optional) | W-2 Social Security wages from another job in 2026; they use up part of the Social Security wage base. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| total | Most you can contribute | Employer contribution + elective deferrals + catch-up (Publication 560 worksheet step 19). |
| employer | Employer contribution | The smallest of net earnings × reduced rate, $360,000 × rate, $72,000 − deferrals and half of (net earnings − deferrals). |
| deferral | Elective deferrals | $24,500 less deferrals to other plans, but no more than what net earnings leave. |
| catchUp | Catch-up contributions | $8,000 at 50 or older, $11,250 at 60 to 63, but no more than what net earnings leave. |
| netEarnings | Net earnings from self-employment | Net profit − the deduction for half of self-employment tax (worksheet step 3). |
| seTax | Self-employment tax | Schedule SE: 12.4% of 92.35% of profit up to the wage base + 2.9% of 92.35% of profit. |
| seDeduction | Deduction for half of self-employment tax | Half of the self-employment tax (worksheet step 2). |

## Method

Self-employment tax = 12.4% × the smaller of 92.35% of profit and ($184,500 − job wages) + 2.9% × 92.35% of profit (none under $400 of net earnings). Net earnings = profit − half of that tax. Employer part = the smallest of net earnings × rate ÷ (1 + rate), $360,000 × rate, $72,000 − deferrals, and (net earnings − deferrals) ÷ 2, where deferrals = the smaller of ($24,500 − deferrals to other plans) and net earnings. Catch-up = the smaller of the age catch-up ($8,000; $11,250 at 60 to 63) and net earnings − employer part − deferrals. Total = employer part + deferrals + catch-up.

## Assumptions

- Tax year 2026 (IRS Notice 2025-67); a sole proprietor or partner with no employees other than a spouse. For an S corporation owner, the employer part is figured on W-2 wages instead.
- Deferrals are made to the full limit before the employer part; Roth deferrals count the same toward the limits.
- Catch-up contributions to other plans are not included. An estimate, not tax advice.

## Worked examples

1. profit = $100,000.00, age = under50, rate = 25% gives seTax = $14,129.55, seDeduction = $7,064.78, netEarnings = $92,935.23, employer = $18,587.05, deferral = $24,500.00, catchUp = $0.00, total = $43,087.05. Source: IRS Publication 560 (2025), chapter 5, Deduction Worksheet for Self-Employed (steps 1 to 21) and Rate Worksheet (rate ÷ (1 + rate)), with the 2026 amounts, https://www.irs.gov/publications/p560; IRS Notice 2025-67 (IRB 2025-49): 2026 limits $24,500 (402(g)), $8,000 catch-up, $11,250 at ages 60 to 63, $72,000 (415(c)), $360,000 (401(a)(17)), https://www.irs.gov/irb/2025-49_IRB; Schedule SE (Form 1040): 92.35% of net profit, 12.4% up to the $184,500 wage base and 2.9%, half deducted.
2. profit = $100,000.00, age = 60, rate = 25% gives employer = $18,587.05, deferral = $24,500.00, catchUp = $11,250.00, total = $54,337.05. Source: IRS Publication 560 (2025), chapter 5, Deduction Worksheet for Self-Employed (steps 1 to 21) and Rate Worksheet (rate ÷ (1 + rate)), with the 2026 amounts, https://www.irs.gov/publications/p560; IRS Notice 2025-67 (IRB 2025-49): 2026 limits $24,500 (402(g)), $8,000 catch-up, $11,250 at ages 60 to 63, $72,000 (415(c)), $360,000 (401(a)(17)), https://www.irs.gov/irb/2025-49_IRB.
3. profit = $400,000.00, age = 50, rate = 25% gives employer = $47,500.00, deferral = $24,500.00, catchUp = $8,000.00, total = $80,000.00. Source: IRS Publication 560 (2025), chapter 5, Deduction Worksheet for Self-Employed (steps 1 to 21) and Rate Worksheet (rate ÷ (1 + rate)), with the 2026 amounts, https://www.irs.gov/publications/p560 (step 10: $72,000 − deferrals); IRS Notice 2025-67 (IRB 2025-49): 2026 limits $24,500 (402(g)), $8,000 catch-up, $11,250 at ages 60 to 63, $72,000 (415(c)), $360,000 (401(a)(17)), https://www.irs.gov/irb/2025-49_IRB; Schedule SE (Form 1040): 92.35% of net profit, 12.4% up to the $184,500 wage base and 2.9%, half deducted.
4. profit = $30,000.00, age = under50, rate = 25% gives netEarnings = $27,880.57, deferral = $24,500.00, employer = $1,690.28, total = $26,190.28. Source: IRS Publication 560 (2025), chapter 5, Deduction Worksheet for Self-Employed (steps 1 to 21) and Rate Worksheet (rate ÷ (1 + rate)), with the 2026 amounts, https://www.irs.gov/publications/p560 (step 12: one-half of net earnings less deferrals).
5. profit = $100,000.00, age = under50, rate = 25%, other = $10,000.00, w2 = $180,000.00 gives seTax = $3,236.15, seDeduction = $1,618.08, deferral = $14,500.00, employer = $19,676.39, total = $34,176.39. Source: IRS Publication 560 (2025), chapter 5, Deduction Worksheet for Self-Employed (steps 1 to 21) and Rate Worksheet (rate ÷ (1 + rate)), with the 2026 amounts, https://www.irs.gov/publications/p560; IRS Notice 2025-67 (IRB 2025-49): 2026 limits $24,500 (402(g)), $8,000 catch-up, $11,250 at ages 60 to 63, $72,000 (415(c)), $360,000 (401(a)(17)), https://www.irs.gov/irb/2025-49_IRB (deferrals to all plans share the limit); Schedule SE (Form 1040): 92.35% of net profit, 12.4% up to the $184,500 wage base and 2.9%, half deducted (line 8a W-2 wages).

## FAQ

### How much can I contribute to a solo 401(k) in 2026?

Elective deferrals of up to $24,500, plus an employer contribution, with the two together capped at $72,000. On top of that, a catch-up of $8,000 at age 50 or older, or $11,250 at ages 60 to 63, for totals of up to $80,000 or $83,250. Your net earnings set the real limit.

### How is the employer contribution figured for the self-employed?

Start from net profit and take off half of your self-employment tax to get net earnings. The employer part is net earnings × rate ÷ (1 + rate): 20% of net earnings for a 25% plan. With $100,000 of profit, net earnings are $92,935.23 and the employer part is $18,587.05.

### Why 20% and not 25%?

For the self-employed, the contribution itself comes out of the earned income it is based on. 25% of what is left after the contribution is the same as 20% of the amount before it: 0.25 ÷ 1.25 = 0.20. IRS Publication 560 calls this the reduced rate.

### I also have a 401(k) at my job. Does that change anything?

Yes. The $24,500 deferral limit is per person across all your plans, so deferrals at your job use part of it; type them in the calculator. The employer contribution to your own plan has its own limit. W-2 wages also use up part of the Social Security wage base, which lowers your self-employment tax.

### Can I make Roth contributions to a solo 401(k)?

If your plan allows it, deferrals and catch-up can be designated Roth contributions. They count toward the same limits, but they are not deductible.

### What if my profit is small?

Contributions cannot be more than your net earnings. With $30,000 of profit, net earnings are $27,880.57: deferrals of $24,500 use most of it and the employer part is limited to half of what is left, $1,690.28, for a total of $26,190.28.

### Does this work for an S corporation owner?

No. If you are paid wages by your own S corporation, the employer part is figured on your W-2 wages (up to 25%), not on net earnings from self-employment. This calculator is for sole proprietors and partners.

## Sources

- IRS, Publication 560 (2025), Retirement Plans for Small Business: chapter 5, Deduction Worksheet for Self-Employed, steps 1 to 21, and the Rate Worksheet for Self-Employed (rate ÷ (1 + rate)); What’s New gives the 2026 limits ($24,500 elective deferrals, $8,000 catch-up, $11,250 at ages 60 to 63). https://www.irs.gov/publications/p560 (retrieved 2026-10-18)
- IRS, Notice 2025-67 (Internal Revenue Bulletin 2025-49), 2026 amounts relating to retirement plans: section 415(c)(1)(A) limit $72,000; section 402(g)(1) $24,500; section 414(v) catch-up $8,000 and $11,250 for ages 60 to 63; section 401(a)(17) compensation $360,000. https://www.irs.gov/irb/2025-49_IRB (retrieved 2026-10-18)
- IRS, 401(k) and profit-sharing plan contribution limits ($72,000 in 2026, $80,000 with catch-up or up to $83,250 at ages 60 to 63; deferrals to all plans are added together; compensation limited to $360,000). https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-401k-and-profit-sharing-plan-contribution-limits (retrieved 2026-10-18)
- IRS, Publication 15 (2026): Social Security wage base $184,500, rates 6.2% and 1.45% (doubled for self-employment tax on Schedule SE, 92.35% of net profit). https://www.irs.gov/publications/p15 (retrieved 2026-10-18)