United States · IRS self-employed retirement
Solo 401(k) and SEP IRA contribution calculator.
Enter your Schedule C net profit and age to see the most you can put away in each plan for 2026.
For 2026 a self-employed person can contribute up to 20% of net profit after half of SE tax to a SEP IRA, capped at $72,000. A solo 401(k) allows the same 20% employer share plus up to $24,500 of employee deferrals, and an extra $8,000 catch-up at 50 or $11,250 at 60-63.
Your numbers
2026 result
How the calculation works
Following the self-employed worksheets in IRS Pub. 560: start with Schedule C net profit. Estimate self-employment tax as 12.4% social security (on 92.35% of profit, up to the $184,500 wage base) plus 2.9% Medicare, and subtract half of it. What remains is your plan compensation, capped at $360,000 for the contribution formula.
SEP IRA: compensation × 20% (the sole-proprietor equivalent of 25%), up to $72,000.
Solo 401(k): employer share = compensation × 20%. Employee deferral = the lesser of $24,500 plus any catch-up, and compensation minus the employer share. The employer share is then trimmed so deferral (excluding catch-up) plus employer share does not exceed $72,000. Catch-up is added on top of the $72,000.
Worked example. $100,000 profit, age 40. SE tax = 92,350 × 15.3% = $14,129.55; half = $7,064.78. Compensation = $92,935.23. SEP = 20% = $18,587.05. Solo 401(k) = $24,500 deferral + $18,587.05 employer = $43,087.05, so the solo plan allows about $24,500 more.
Limits and sources
| Item | 2026 value | Primary source |
|---|---|---|
| Defined contribution limit, section 415(c) | $72,000 | IRS Notice 2025-67 |
| Employee deferral limit, section 402(g) | $24,500 | IRS Notice 2025-67 |
| Catch-up, age 50 or older | $8,000 | IRS Notice 2025-67 |
| Catch-up, age 60 to 63 | $11,250 | IRS Notice 2025-67 |
| Compensation limit, section 401(a)(17) | $360,000 | IRS Notice 2025-67 |
| Self-employed plan rate and worksheets | 20% of net earnings after half of SE tax | IRS Pub. 560 |
| Social security wage base | $184,500 | SSA contribution and benefit base |
| Annual limits summary | All of the above | IRS COLA page |
Rules as of October 2, 2026. Not modelled: wages from another job (they share the wage base and your $24,500 deferral limit), employees, Roth deferrals, state tax, and additional Medicare tax. All limits sit in one constants block in the page script, so they can be updated each year. Pub. 560 is revised annually.
Cite this page: TNAADO Tools, "Solo 401(k) and SEP IRA Contribution Calculator 2026," https://tools.tnaado.ca/us/solo-401k-sep-ira-contribution-calculator.html, rules as of October 2, 2026, from IRS Notice 2025-67 and Pub. 560.
Frequently asked questions
What is the SEP IRA contribution limit for the self-employed in 2026?
The lesser of 25% of compensation and $72,000, and for a sole proprietor 25% of compensation works out to 20% of net profit after subtracting half of your self-employment tax. The $72,000 figure is the section 415(c) limit in IRS Notice 2025-67. Compensation counted is capped at $360,000, so the 20% share tops out at $72,000.
What is the solo 401(k) limit for 2026?
Employee deferrals up to $24,500 (or your earned income if lower), plus an employer profit-sharing contribution of up to 20% of your net profit after half of SE tax. The two together are capped at $72,000, and the catch-up is added on top: $8,000 at age 50 or older, or $11,250 if you are 60, 61, 62 or 63 in 2026. That makes $80,000 at 50-59 and 64+, and $83,250 at 60-63.
Why is my solo 401(k) limit higher than a SEP IRA at the same profit?
A SEP has only the employer share, 20% of net profit. A solo 401(k) adds a deferral of up to $24,500 that is not tied to a percentage, so at lower profits it lets you save far more. Above roughly $237,500 of compensation the $72,000 cap catches up and the base limit is the same, though the solo 401(k) still allows the catch-up.
Why is it 20% and not 25%?
The 25% plan rate applies to compensation after your own contribution is subtracted. A sole proprietor's contribution comes out of the same profit it is based on, so Pub. 560 converts 25% into 20% of net earnings (0.25 divided by 1.25). Corporations paying W-2 wages use the straight 25%.
When do I have to make the contribution?
Employer contributions, including a SEP, can generally be made up to the due date of your return including extensions. Deferrals to a solo 401(k) have separate set-up and election rules, and SECURE 2.0 changed them for some first-time sole proprietor plans, so check Pub. 560 or your plan provider before relying on a date.
Can I have a SEP IRA and a solo 401(k)?
Contributions to both for the same business share one $72,000 employer limit under section 415(c), so there is no reason to fund both. If you also have a 401(k) at a day job, your $24,500 deferral limit is shared across all plans, which this calculator does not model.
Estimate only
This is an educational calculation, not tax or investment advice. Your exact limit depends on your final Schedule C and SE tax, other plans and entity type. Confirm with a qualified tax professional before contributing.