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How much can this practice put into a SEP, a solo 401(k) or a SIMPLE this year?
Enter your profit, your age and how you file. The page applies the 2026 limits from IRS Notice 2025-67 and Publication 560’s 20% rule to all three plans, then prices what the contribution saves in this year’s federal and California income tax.
Your numbers →Your numbers
Four facts decide the ceiling. None of them is a guess.
Profit is collected fees less practice costs before any tax, as a sole proprietor — the figure the practice simulator produces. If the practice is a professional corporation with S-corp treatment, switch the entity and enter the W-2 wage it pays you; the arithmetic changes shape. Age sets the catch-up. Filing status sets the tax saved. Deferrals already made this year into another employer’s 401(k) or 403(b) count against the same $24,500.
Across profit levels
The same three plans at seven profit levels, with your age and entity.
| Profit (or wage) | SEP-IRA | Solo 401(k) | SIMPLE IRA |
|---|---|---|---|
| $50,000 | — | — | — |
| $80,000 | — | — | — |
| $110,000 | — | — | — |
| $150,000 | — | — | — |
| $200,000 | — | — | — |
| $250,000 | — | — | — |
| $300,000 | — | — | — |
Sole proprietor figures use the profit; S-corp figures treat the level as the W-2 wage. The solo 401(k) column is the SEP column plus the deferral until the $72,000 ceiling binds, which for a sole proprietor under 50 happens near $252,000 of profit.
How it computes
One base, three rules, and a ceiling.
Net earnings from self-employment are 92.35% of profit. Self-employment tax is 12.4% of those earnings up to $184,500 plus 2.9% on all of them; half of it is deducted from profit, and what is left is the compensation every plan measures from (Publication 560). No plan changes the self-employment tax itself.
The contribution is a percentage of compensation after the contribution itself comes out, so C = 0.25 × (B − C), which solves to C = 0.2B exactly — the .200000 in Publication 560’s rate table. Capped at $72,000 (§415(c)) and at $360,000 of compensation. For an S-corp wage there is no circularity: 25% of the W-2 figure.
Elective deferrals are not counted against the employer limit (§404(n)), so the deferral of $24,500 sits on top of the SEP figure until the pair reaches $72,000 or 100% of compensation. The catch-up — $8,000 from 50, $11,250 at 60 to 63 instead — is allowed above the $72,000. Deferrals already made into another employer’s plan this year reduce the $24,500, because that limit belongs to the person.
An employer with 25 or fewer employees gets the $18,100 deferral automatically, and its catch-up at 50 is $3,850 rather than $4,000; at 60 to 63 it is $5,250. The match is 3% of net earnings from self-employment before any contribution (or of the wage). A SIMPLE is exclusive: no other plan in the same year.
The contribution is deducted from adjusted gross income and from qualified business income, then the 2026 federal schedule and the 2025 California schedule are applied, exactly as the other money pages do. Self-employment tax is unchanged. The S-corp case is left to the tax-strategy page, because the corporation’s deduction and the wage interact.
Then what
The ceiling is arithmetic. The choice is not.
The decision
Solo 401(k), SEP or SIMPLE: what a California therapist should open
Deadlines, Roth options, what employing anyone changes, the S-corp inversion, and why the 25% is really 20% — the guide this calculator is built on.
Every account, priced together
How much of my tax bill is optional?
Retirement accounts, the health premium, the entity choice and what each is worth against your own profit.
The quarterly consequence
The estimated tax calculator
A contribution lowers the tax the safe harbor is measured against; this is what changes in the four payments.
Where every figure came from
Sources.
The 2026 limits
The rules
The engine
The constants are the ones the practice simulator, the tax-strategy page and the estimated-tax calculator use, copied rather than restated. Married filing separately is not modeled. Roth versions of each plan change when the tax is paid, not how much can go in.
