The IRS Dollar Limit Sets Your Ceiling

For 2025, the IRS caps the annual addition to a defined contribution plan, including a profit sharing plan, at $70,000 per participant under IRC Section 415(c). The 25% of compensation limit applies first. Whichever is lower controls. For employees, compensation is W-2 wages. For self-employed owners, compensation is a calculated net figure, not gross revenue.

A solo operator with $400,000 in net self-employment income does not contribute $100,000 (25% of $400,000). The $70,000 ceiling applies first, and the IRS compensation calculation reduces the effective base further. The $70,000 limit indexes annually with inflation. Check IRS Publication 560 each year before funding your plan.

Why Self-Employed Owners Face a Different Formula

Self-employed owners cannot use the simple 25% rate that applies to W-2 employees. The IRS treats the profit sharing contribution itself as a deduction that reduces the compensation base used to calculate that same contribution. This circular design requires a different approach.

The solution is the rate table in IRS Publication 560. For a plan with a stated contribution rate of 25%, the effective self-employed rate is 20%. The math behind that factor:

Effective rate = Stated rate / (1 + Stated rate) = 0.25 / (1 + 0.25) = 0.20

Applying 20% to the correct net income figure produces the same dollar result as the full circular calculation. No iteration required.

How to Calculate Net Self-Employment Income Correctly

Net self-employment income for profit sharing purposes is not your Schedule C net profit. Two adjustments apply before you multiply by 20%.

Step 1: Calculate self-employment tax on your Schedule C net profit. Multiply Schedule C net profit by 0.9235, then multiply that result by 15.3%. That is your gross self-employment tax. Half of that amount, the Section 164(f) deduction, reduces your adjusted net profit.

Step 2: Subtract the Section 164(f) deduction from Schedule C net profit. The result is your net self-employment income for contribution purposes.

Step 3: Multiply by 0.20.

Worked Example 1: Solo Operator, $150,000 Schedule C Net Profit

Schedule C net profit: $150,000

Self-employment tax base: $150,000 x 0.9235 = $138,525

Self-employment tax (at 15.3%): $138,525 x 0.153 = $21,194

Section 164(f) deduction (half): $21,194 / 2 = $10,597

Net self-employment income: $150,000 - $10,597 = $139,403

Maximum profit sharing contribution: $139,403 x 0.20 = $27,881

That $27,881 is deductible on Schedule 1, Line 16 of Form 1040. A business owner using the incorrect gross figure of $150,000 x 0.25 would claim $37,500. The $9,619 overclaim is an excess contribution subject to a 10% excise tax under IRS Form 5330 plus potential plan disqualification.

Worked Example 2: Solo Operator, $280,000 Schedule C Net Profit

Schedule C net profit: $280,000

Self-employment tax base: $280,000 x 0.9235 = $258,580

Self-employment tax: $258,580 x 0.153 = $39,563 (Note: Only $168,600 of wages are subject to the 12.4% Social Security portion in 2025. The 2.9% Medicare portion applies to all earnings. The blended calculation here uses IRS tables. Consult IRS Schedule SE for the exact split.)

Section 164(f) deduction: $39,563 / 2 = $19,782

Net self-employment income: $280,000 - $19,782 = $260,218

Contribution at 20%: $260,218 x 0.20 = $52,044

The $70,000 Section 415(c) ceiling does not bind here. The contribution is $52,044. Had this owner applied 25% to the $280,000 gross figure, the claimed deduction would be $70,000. That $17,956 overclaim triggers Form 5330 and a $1,796 excise tax, before penalties.

Contributions for W-2 Employees in a Small Business Plan

When a small business with a profit sharing plan employs W-2 workers, the formula changes. Contributions for employees use W-2 box 1 compensation directly. The 25% rate applies without the circular adjustment. A W-2 employee earning $80,000 receives a maximum profit sharing allocation of $20,000.

The employer must use a nondiscrimination-tested allocation formula. The most common is the pro-rata formula: each eligible participant receives the same percentage of their compensation. If the owner contributes 20% of net self-employment income, the plan must generally contribute the same percentage of W-2 wages for eligible employees. A plan document specifying a different formula must pass IRS nondiscrimination testing under IRC Section 401(a)(4).

Contribution Deadlines and Funding Mechanics

Profit sharing plan contributions for a given tax year are due by the employer's tax return due date, including extensions. For a sole proprietor filing Schedule C, that is April 15, 2026, for the 2025 tax year, extended to October 15, 2026, with a timely filed Form 4868.

You must adopt the plan itself before December 31 of the tax year. A solo 401(k) with a profit sharing component adopted on December 30, 2025, allows a contribution funded as late as October 15, 2026, if an extension is filed. A SEP-IRA follows the same deadline logic but does not require adoption by year-end.

Contributions must be in cash. You cannot contribute securities or other property to a profit sharing plan under IRC Section 404.

Run Your Numbers Before You Fund

Funding a profit sharing plan on estimated figures and correcting it later is expensive. Excess contributions accumulate a 10% excise tax under IRC Section 4972 for every year they remain in the plan. Correcting them requires a corrective distribution, taxable to the participant, plus potential plan amendment through the IRS Employee Plans Compliance Resolution System.

The CalcMoney Self-Employment Tax Calculator computes your Schedule C net profit, self-employment tax, Section 164(f) deduction, and contribution base in one pass. Enter your gross revenue and deductible expenses. The calculator outputs the exact dollar figure to apply the 0.20 factor against, before you write the check to your plan custodian.

Run your profit sharing contribution calculation now →

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This article is for informational purposes only and does not constitute financial, tax, or legal advice. Consult a qualified tax professional or financial advisor before making contribution decisions or amendments to retirement plans.