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US Small Business C-Corp Tax Formula:
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The US Small Business C-Corporation tax is calculated at a flat rate of 21% on taxable income for the 2025 tax year. This rate applies to most C-corporations regardless of income level.
The calculator uses the simple tax formula:
Where:
Explanation: The calculation multiplies taxable income by the flat corporate tax rate of 21% to determine the total tax liability.
Details: Accurate tax calculation is essential for business planning, budgeting, compliance with IRS regulations, and avoiding penalties for underpayment.
Tips: Enter taxable income in USD. The value must be non-negative. The calculator will automatically compute the tax amount at the current 21% corporate rate.
Q1: What is the current US corporate tax rate?
A: For 2025, the federal corporate tax rate is 21% for most C-corporations.
Q2: Does this include state and local taxes?
A: No, this calculator only computes federal corporate tax. State and local taxes vary by jurisdiction and must be calculated separately.
Q3: What is considered taxable income for a C-corp?
A: Taxable income generally includes gross income minus allowable business deductions and expenses.
Q4: Are there different rates for different income levels?
A: No, the 21% rate is a flat tax that applies to all taxable income levels for C-corporations.
Q5: When are corporate tax payments due?
A: Corporations typically make estimated tax payments quarterly and file annual returns by the 15th day of the 4th month following the end of their tax year.