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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.
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
Also read
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.
Read 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.
Read 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.
ReadWork with Matt
Ready to build a plan?
Matt Reese, CPA works with S-corp owners to maximize retirement contributions and coordinate them with reasonable compensation, entity structure, and the full tax plan.
Tax services provided through Matt Reese, CPA. This page is educational and does not constitute tax or investment advice.