How to Calculate Corporate Income Tax
Corporate income tax equals the statutory rate times taxable profit, which is revenue minus deductible costs, so the tax falls on the margin and not on sales.
The Corporate Income Tax formula
Calculator
Enter revenue, deductible costs and the tax rate to get taxable profit, the tax owed and the second layer on dividends.
Total sales for the year. The tax is not charged on this figure.
Wages, materials, rent, interest paid and depreciation.
The rate applied to taxable profit, not to sales.
What shareholders pay on the profit once it is paid out. Set it to 0 to see the corporate layer alone.
The rate applied to taxable profit gives a bill of $3 million.
- Taxable profit
- $12 million
- After-tax profit
- $9 million
- Tax on dividends paid out
- $1.35 million
- Combined tax as a share of profit
- 36.25%
- Corporate tax as a share of revenue
- 7.5%
Revenue minus deductible costs leaves $12 million, and that margin is the whole tax base.
$9 million stays with the firm to reinvest or hand to shareholders.
Paying the whole after-tax profit out as dividends triggers another $1.35 million in shareholders' hands.
Both layers together take 36.25% of the profit, which is the double taxation argument in one number.
The bill is only 7.5% of sales, which is why a corporate tax is not a sales tax.
How to calculate Corporate Income Tax, step by step
- 1Start from revenue. Take total sales for the year. This is the top line, and it is not the figure the rate applies to.
- 2Subtract every deductible cost. Wages, materials, rent, interest paid and depreciation on capital all come out. What is left is taxable profit, and a firm running a loss has none.
- 3Apply the statutory rate. Tax owed = rate × taxable profit. A firm with large sales and thin margins owes very little, because the base is the margin rather than the sales.
- 4Add the shareholder layer if the question asks. Profit paid out as dividends is taxed again in shareholders' hands, so add that second bill to see the combined take on one year of profit.
Worked example: Corporate Income Tax
A firm sells $40 million of goods and deducts $28 million of wages, materials, interest and depreciation, so taxable profit = 40 − 28 = $12 million. At an illustrative 25% rate, tax owed = 0.25 × $12 million = $3 million, leaving $9 million after tax. That $3 million is 7.5% of revenue, because the rate is charged on the $12 million margin rather than on the $40 million of sales. If the whole $9 million goes out as dividends taxed at an illustrative 15%, shareholders owe another 0.15 × $9 million = $1.35 million, so the combined bill on that profit is 3 + 1.35 = $4.35 million, or 36.25% of it.
Corporate Income Tax questions
Is corporate income tax charged on revenue or on profit?
On profit. The rate applies to revenue minus deductible costs, so two firms with identical sales can owe very different amounts when one carries higher costs, and a firm making a loss owes nothing.
What is double taxation of corporate profits?
The same profit is taxed once at the company level and again when it reaches shareholders as dividends or capital gains. Business forms that pass income straight through to their owners, such as partnerships, skip the first layer.
Why is a firm's effective rate usually below the statutory rate?
Deductions, credits and depreciation rules shrink taxable profit below the profit reported to investors, so tax paid divided by profit comes out under the headline rate. That gap is why economists compare effective rates rather than statutory ones.
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