How the SCorpMath calculator works

SCorpMath estimates the difference between two simplified scenarios: a sole proprietor or disregarded LLC paying self-employment tax on net earnings, and an S-Corp shareholder-employee receiving a salary subject to payroll taxes with remaining profit treated as estimated distributions.

The result is a rough planning estimate. It is designed to help you prepare better questions for a qualified tax professional, not to decide whether you should elect S-Corp status.

The calculator estimates self-employment tax for sole proprietor or disregarded LLC treatment, then compares it with payroll taxes on an assumed S-Corp shareholder-employee salary. It also subtracts user-entered S-Corp administrative costs.

• Tax year and Social Security wage base assumptions.
• Net business profit before owner salary.
• Filing status for Additional Medicare Tax threshold logic.
• Estimated reasonable S-Corp salary entered by the user.
• Estimated annual S-Corp admin costs entered by the user.
• Optional other W-2 wages that may reduce remaining Social Security wage base.

These are the main constants and boundaries used by the current calculator model. They describe how SCorpMath produces a rough estimate; they are not instructions for completing a return or choosing an entity treatment.

Constants are maintained in the versioned calculator configuration. Official IRS and SSA sources are linked below; state-specific pages identify additional items that the federal model does not calculate.

In the sole proprietor or disregarded LLC scenario, SCorpMath starts with annual net business profit and applies a simplified Schedule SE-style adjustment to estimate net earnings subject to self-employment tax. It then estimates the Social Security portion up to the annual wage base and the Medicare portion on applicable net earnings.

If other W-2 wages are entered, the calculator reduces the remaining Social Security wage base available for the self-employment tax estimate. This can materially change the comparison for users who have both W-2 wages and self-employment income.

In the S-Corp scenario, SCorpMath treats the entered salary as wages subject to payroll tax assumptions. Remaining profit after salary and estimated employer payroll taxes is shown as an estimated distribution before admin costs.

The calculator can include estimated employer payroll taxes as an economic cost of the S-Corp scenario. It then subtracts user-entered admin costs such as payroll software, bookkeeping, tax filing, registered agent, and state compliance costs.

For a narrower explanation of salary payroll taxes, see the S-Corp payroll tax calculator.

The simplified gross tax difference is the estimated sole proprietor / LLC self-employment tax minus the estimated S-Corp payroll tax. The estimated net difference subtracts annual S-Corp admin costs from that gross difference.

The MVP does not calculate complete federal income tax, state income tax, QBI, retirement contributions, accountable plans, shareholder basis, health insurance treatment, Form 1120-S, or state-specific entity taxes.

It also does not determine eligibility for S-Corp election, file Form 2553, model late election relief, compare entity legal liability, or analyze state franchise, gross receipts, city, or payroll tax rules.

SCorpMath does not determine reasonable compensation. Salary assumptions should be reviewed with a qualified tax professional because the right salary depends on services performed, duties, time, skill, comparable pay, and the facts of the business.

A lower salary can make the calculator result look more favorable. That does not mean the salary is supportable. Use the warning messages as a prompt to discuss the assumption, not as a safe harbor.

Annual tax constants live in a versioned configuration file. Before each tax season, SCorpMath should verify the Social Security wage base, IRS self-employment tax guidance, Additional Medicare Tax thresholds, Form 2553 instructions, and S-Corp compensation guidance.

The calculator currently supports 2025 and 2026 assumptions. If a tax year is not available, users should not extrapolate from old numbers without professional review.

If the estimated net difference is small, S-Corp complexity may not be worth much attention unless there are other reasons to review entity treatment. If the estimate is material, the next step is to bring the assumptions to a qualified CPA, EA, tax attorney, payroll professional, or other qualified advisor.

You can return to the SCorpMath calculator and test different salary and admin cost assumptions before that discussion.