A C corporation is the only business structure in the United States that is taxed twice: once at the company level on its profits, and again at the shareholder level when those profits leave the company as dividends. This C-corp tax calculator shows you exactly how that split works — the flat 21% federal corporate rate, your state's corporate tax, and the 15% qualified-dividend tax your owners pay on top — so you can see the true effective tax burden on every dollar the business earns.
Adjust the sliders and every figure updates instantly. Slide the dividend payout ratio down to zero and watch the second tax layer disappear, which is the core insight behind why growing companies often retain earnings instead of paying them out.
How to Use
- Enter your Annual Taxable Income — the corporation's profit after ordinary business expenses but before any tax. This is the number on line 28 of Form 1120.
- Set your State Corporate Tax Rate. The US average is about 5%, but rates range from 0% (Nevada, Texas, Washington, Wyoming and a handful of others) up to around 9–12% in the highest-tax states. If you are incorporated in a state with no corporate income tax, enter 0.
- Choose your Dividend Payout Ratio — the share of after-tax profit you actually distribute to shareholders. Leave it at 100% to see the full double-taxed picture, or lower it to model retained earnings that stay inside the company.
- Set the Qualified Dividend Rate for your owners. Most shareholders pay 15%; lower-income households qualify for 0%, and the top bracket pays 20%. Ordinary (non-qualified) dividends are taxed at your ordinary income rate, which can be much higher.
The result card breaks out state tax, federal tax, the total corporate-level bill, the dividends paid, the shareholder's dividend tax, retained earnings, and the combined effective double-tax rate on the original profit.
How C-Corporation Tax Works
Since the 2017 Tax Cuts and Jobs Act, the federal corporate income tax has been a single flat rate of 21% on every dollar of taxable profit — there are no graduated brackets below the way there are for individuals. State corporate income tax is then added on top, but it is deductible on the federal return, which slightly softens the blow. The math runs like this:
- State tax = taxable income × your state rate.
- Federal tax = (taxable income − state tax) × 21%.
- Total corporate tax = federal + state.
- After-tax profit = taxable income − total corporate tax.
On a $200,000 profit at a 5% state rate: state tax is $10,000, federal tax is $39,900 (because the $10,000 state tax is deducted first), and the combined corporate-level bill is $49,900, leaving $150,100 of after-tax profit. That blended corporate rate is 24.95% — higher than the headline 21% once the state layer is stacked on.
This is where the famous "double taxation" arrives. If the corporation pays the full $150,100 out as dividends, each shareholder adds a 15% qualified-dividend tax — another $22,515 — leaving shareholders with $127,585. The taxman has now taken $72,415 of the original $200,000, an effective double-tax rate of 36.21%.
Why Retained Earnings Matter
The second tax layer only triggers when money actually leaves the company. If the board keeps all $150,100 inside the business to fund growth, equipment, or a safety cushion, the shareholder pays no dividend tax at all. The total tax paid stays at $49,900 — a 24.95% effective rate, not 36.21%. That gap is why reinvesting companies delay dividends, why a 401(k) or qualified small-business-stock election can change the math, and why many founders pay themselves a modest salary and leave the rest in the corporation until a liquidity event (a sale or qualified IPO) locks up the lower long-term treatment.
Compare that with an S corporation or LLC, where profit passes straight through to the owner's personal return and is taxed only once. The C-corp trade-off is simpler ownership, unlimited investors, and cheaper fringe benefits — paid for by this second tax layer on distributed profit.
Examples
Example 1 — A small $200,000 SABIC. A $200,000 profit, 5% state rate, 100% payout, 15% dividend rate: state tax $10,000, federal tax $39,900, dividends $150,100, shareholder dividend tax $22,515, and total tax to all governments $72,415. Shareholders walk away with $127,585 — a 36.21% combined drag on the original profit.
Example 2 — Bootstrapping growth, no dividends. Same $200,000 profit, but the board pays out 0% of after-tax earnings. Corporate tax is still $49,900, but with no dividends there is no shareholder dividend tax. The full $150,100 sits as retained earnings, the effective rate is just 24.95%, and the company has capital it can deploy without a second tax bite.
Example 3 — A $2 million business. At $2,000,000 of profit with the same 5% state rate and full payout, state tax is $100,000, federal tax is $399,000, dividends are $1,501,000, and the shareholder's dividend tax alone is $225,150. Total tax across both layers is $724,150 — the effective rate stays 36.21% because the model is flat and proportional.
FAQ
What is the federal C-corporate tax rate?
Since the Tax Cuts and Jobs Act took effect in 2018, the federal corporate income tax has been a flat 21% on taxable income, regardless of profit level. There are no graduated brackets. State corporate income tax is added on top and is deductible against federal taxable income.
How does double taxation actually work?
First, the corporation pays tax on its profits — 21% federal plus your state rate. Then, when whatever is left is paid to shareholders as dividends, those dividends are taxed again on the owners' personal returns at the qualified-dividend rate (usually 15%). If earnings are retained inside the company, the second layer never triggers.
Are all dividends taxed at 15%?
No. Qualified dividends (stock held more than 61 days in the 121-day window around the ex-dividend date) are taxed at 0%, 15%, or 20% depending on the owner's taxable income. Most middle- and upper-middle-income shareholders pay 15%. Ordinary or non-qualified dividends are taxed at your ordinary income rate, which can reach 37%, so holding period matters a lot.
What states have no corporate income tax?
Nevada, Ohio, Texas, Washington and Wyoming levy no traditional corporate income tax, and South Dakota has none on most corporations. Several other states tax gross receipts rather than net profit. If your corporation is based in one of these, set the state rate to 0% in this calculator to see the federal-only picture.
When should a C-corp pay dividends versus retain earnings?
Pay dividends when the shareholders need cash and their qualified-dividend rate is low (0% or 15%). Retain earnings when the business can reinvest the money at a return above the shareholder's alternative, or when the owners are planning a qualified small business stock sale that can exclude up to 100% of the later gain. Sliding the payout ratio on this page shows the immediate tax gap.
How is a C-corp different from an S-corp or LLC?
An S-corp or LLC is a pass-through entity: profit is taxed once, on the owner's personal return, and there is no second layer when money moves to the owner. A C-corp pays the 21% corporate tax itself and then may trigger a shareholder tax on dividends. The C-corp's advantages are unlimited investors, easier venture-capital funding, and deductibility of many fringe benefits.
Disclaimer
This C-corp tax calculator is provided for informational purposes only and does not constitute tax, legal, or accounting advice. It applies a simplified flat 21% federal corporate rate and a single flat state rate; actual corporate tax returns include deductions, credits, net operating losses, depreciation, state-specific schedules, and surcharges that this tool does not model. Dividend treatment depends on holding period and personal income. Always confirm your real liability with a qualified CPA or tax professional before filing.