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Retirement contribution maximizer.
Find out how much you can contribute to a Solo 401(k), SEP-IRA, or SIMPLE IRA based on your self-employment income — and see your estimated tax savings and after-tax cost at your marginal rate.
Not sure how this works? Read the guide
Your numbers
2026 contribution limits
Marginal rate: 24%
Solo 401(k) ★
$54,500
SEP-IRA
$30,000
SIMPLE IRA
$21,500
| Solo 401(k)★ | SEP-IRA | SIMPLE IRA | |
|---|---|---|---|
| Employee deferral | $24,500 | — | $17,000 |
| Employer contribution | $30,000 | $30,000 | $4,500 |
| Total max contribution | $54,500 | $30,000 | $21,500 |
| Est. federal tax savings | $13,080 | $7,200 | $5,160 |
| After-tax cost | $41,420 | $22,800 | $16,340 |
| Deadline | Establish by Oct 15 (tax year); fund by tax filing deadline (incl. extensions) | Establish and fund by tax filing deadline (incl. extensions) | Must be established by Oct 1 of the year being funded |
Best plan for your situation
Solo 401(k) allows the highest contribution for most owners earning above $100,000. It's the highest-leverage retirement deduction available to you.
Roth Solo 401(k) option
Solo 401(k) also offers a Roth contribution option on the employee deferral — allowing after-tax contributions that grow tax-free. Consult your plan provider.
Read next
Solo 401(k), SEP-IRA, and SIMPLE IRA: Which Retirement Plan Is Right for Your Business?
The three main retirement plans for self-employed business owners compared — contribution limits, who qualifies, deadline rules, and when each one makes sense. With 2025 limits.
Tax planningDefined Benefit and Cash Balance Plans: The High-Income Owner's $200,000+ Deduction
Solo 401(k) contributions cap out around $70,000. A cash balance plan can let a profitable business owner deduct $150,000 to $350,000 per year — dramatically lowering current-year tax bills while building a guaranteed retirement benefit.
Tax planningBackdoor Roth IRA: How High-Income Earners Get Money Into a Roth
High earners above the Roth IRA income limit can contribute via the backdoor — contribute nondeductibly to a traditional IRA, then immediately convert to Roth. The pro-rata trap, how to avoid it, and the mega backdoor Roth for up to $46,500/year.
Tax data sources
- IRC §401(k) — Qualified cash or deferred arrangements
- IRC §402A — Optional treatment of elective deferrals as Roth contributions
- IRC §408 — Individual retirement accounts
- IRC §404 — Deduction for contributions to employee benefit plans
- Rev. Proc. 2024-40 — 2025 retirement contribution limits
- IRS Pub. 560 — Retirement Plans for Small Business