Key takeaway: Compare the corporation’s tax and cash with the owners’ tax and cash separately. Then test investor eligibility, equity rights, reinvestment, compliance and the expected sale. A single tax rate does not determine the best structure.
C and S corporation taxation can produce different results for the same operating business. A useful model states the tax year, salary, payroll costs, distributions and owner assumptions, then projects several years and an exit.
Separate legal form from tax classification
A state-law corporation generally has C corporation taxation unless it makes a valid S election. An LLC is a legal form with separate federal classification rules; it may be disregarded, a partnership or taxed as a corporation depending on its owners and elections. This comparison assumes the business is taxed as either a C or S corporation. See the IRS LLC classification guidance.
Understand the two tax structures
A C corporation generally files Form 1120 and pays federal income tax at 21% of taxable income. Tax applies to its taxable income whether cash is retained or distributed. Distributions out of current or accumulated earnings and profits generally create dividends for shareholders; distributions beyond earnings and profits have separate basis and gain rules. State taxes and special corporate taxes may also apply. See IRS Publication 542.
An S corporation files Form 1120-S and allocates tax items to shareholders on Schedule K-1. Shareholders report those items on their applicable returns, generally even without a cash distribution. S corporations can still owe entity-level taxes, including built-in gains and excess net passive income tax when the relevant conditions apply. See the Form 1120-S instructions.
A non-dividend S corporation distribution generally reduces stock basis and is tax-free only to that extent; an excess can create gain. Debt basis is not used to shelter distributions. Prior C corporation earnings and profits can introduce dividend treatment. Retained taxable income generally increases stock basis, while book equity, accumulated adjustments and cash are different measures. The IRS stock-and-debt-basis guidance explains these distinctions.
State the assumptions behind any combined rate
For a federal-only illustration, assume $100 of C corporation taxable income, 21% corporate tax, and distribution of all $79 remaining as a qualified dividend. If that shareholder pays 20% qualified-dividend tax and the full 3.8% net investment income tax on the dividend, shareholder tax is $79 × 23.8% = $18.802. Total federal tax is $21 + $18.802 = $39.802, or about 39.8%.
That is one scenario, not a universal rate. Qualified dividends can receive other rates, some dividends are ordinary, and NIIT depends on the shareholder’s income and circumstances. The illustration excludes state tax and special corporate taxes. See the IRS guidance on dividends and NIIT. Retaining earnings can defer shareholder dividend tax, but later distributions or liquidation may still create a second layer. Accumulated-earnings and personal-holding-company rules also warrant review.
Model QBI separately
The section 199A qualified business income deduction can affect eligible pass-through income. It does not apply to C corporation income or employee wages, including S corporation wages. The regular calculation depends on taxable income, the business type, qualifying income and applicable wage/property limits. See the IRS QBI overview.
The deduction is permanent under current law. Beginning in 2026, an eligible taxpayer with at least $1,000 of total QBI from active trades or businesses may qualify for a minimum $400 deduction. This has its own eligibility rules, including material participation, and should be tested separately from the regular calculation. See 2026 Publication 505, page 2, and section 199A’s minimum-deduction provision. Do not treat $400 as a tax credit or an automatic S corporation benefit.
Worked example: corporate cash after tax and distributions
Assume $200,000 profit before owner pay, a defensible $90,000 salary, and a rounded $7,000 employer payroll-tax cost under either structure. Both have $103,000 profit before entity income tax. Assume book profit equals taxable income and converts fully to cash for this simplified example, with no beginning cash, working-capital changes, asset purchases, borrowing or other costs.
Both businesses distribute $60,000. The S corporation has no special entity income tax in this example, sufficient shareholder stock basis and no accumulated C corporation earnings and profits. The C corporation’s payment is a dividend. State taxes and QBI are excluded.
| Annual calculation | S corporation | C corporation |
|---|---|---|
| Profit before owner salary and employer payroll tax | $200,000 | $200,000 |
| Owner salary | ($90,000) | ($90,000) |
| Employer payroll tax, assumed | ($7,000) | ($7,000) |
| Profit before entity income tax | $103,000 | $103,000 |
| Federal entity income tax | $0 | ($21,630) |
| Cash before distribution | $103,000 | $81,370 |
| Cash distribution | ($60,000) | ($60,000) |
| Cash retained from modeled annual profit | $43,000 | $21,370 |
The C corporation calculation is $103,000 × 21% = $21,630 tax, leaving $103,000 − $21,630 − $60,000 = $21,370. The S corporation shareholder generally reports the full $103,000 pass-through profit and $90,000 wages, despite receiving only $60,000 of distributions. The C corporation shareholder reports wages and the dividend separately.
Employee Social Security and Medicare withholding reduces the owner’s net paycheck and is separate from the employer’s payroll expense. Apply actual payroll rates and wage bases in a real model. An assumed 37% marginal income-tax rate does not calculate the owner’s total tax: filing status, other income, deductions, credits, dividend rates and NIIT matter.
The retained-cash row alone does not identify the better choice. Calculate each owner’s after-tax cash and each company’s cash needed for operations. Neither salary nor distribution amounts establish reasonable compensation merely because they make the model attractive.
Compare capital, compliance and exit requirements
| Decision | What to evaluate |
|---|---|
| Investors and equity rights | S status has shareholder eligibility, shareholder-count and one-class-of-stock restrictions. C corporation treatment permits a broader range of investors and equity arrangements. |
| Reinvestment | Model corporate and owner tax, distributions needed to fund owner tax, and cash required for growth. |
| Payroll and returns | Both structures can require payroll for owner-employees, separate corporate returns and ongoing records. Compare actual costs for both. |
| Asset sale or stock sale | Model entity gain, owner gain, basis, recapture, distribution or liquidation, and any available elections. |
| Changing classification | Review eligibility, deadlines, built-in gains, prior earnings and profits and restrictions on later changes before electing or revoking S status. |
Review S eligibility under the Form 2553 instructions. Potential qualified-small-business-stock treatment needs a separate analysis of the issuer, original issuance, acquisition date, holding period, business activity and statutory limits. C status alone does not establish section 1202 eligibility; use the current statute and the actual stock history.
Obtain comparable service quotes
CPA Firm South Florida’s published pricing gives a typical $1,000–$3,500 Form 1120-S range including required K-1s, with return-related cleanup included in the quoted fee. Obtain a C corporation quote for comparable work. Separately identify owner personal returns, state returns, payroll, bookkeeping and planning. A Schedule C price is not a C corporation price.
Bring projections, owner pay, current returns, basis records, planned distributions, investor requirements and exit expectations to a tax-planning discussion. Run alternative profit and distribution scenarios and coordinate legal formation or governance changes with counsel.
Frequently asked questions
Are all S corporation distributions tax-free?
No. A non-dividend distribution is generally tax-free only to the extent of stock basis and reduces that basis. Debt basis does not protect a distribution. Prior C corporation earnings and profits can introduce dividend treatment, and excess distributions can create gain.
Does keeping profit in an S corporation postpone the shareholder’s tax?
Generally no. Shareholders report their allocated taxable income even if cash stays in the corporation. Retained income generally increases stock basis, which must be tracked separately from the bank balance and book equity.
Does a C corporation always face a 40% combined tax rate?
No. The combined rate depends on corporate tax, dividend qualification and rates, net investment income tax, state taxes and other facts. The roughly 39.8% federal illustration assumes a 21% corporate rate followed by a 20% qualified-dividend rate plus 3.8% NIIT on all remaining distributed earnings.
Is payroll a cost unique to S corporations?
No. Both C and S corporations can have owner-employees and employment-tax obligations. Compare actual payroll, compensation, filing and recordkeeping costs for both structures rather than treating the C corporation as payroll-free.