Estimate Your C-Corp Federal Taxes in Minutes.
Calculate quarterly estimated payments and your annual federal tax liability for your corporation.
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*This calculator provides a simplified estimate only — it does not account for state taxes, alternative minimum tax, unusual circumstances, or every credit that may apply, and does not replace professional tax advice.
There are Three Benefits of Planning Your Taxes with the FastLLC Calculator
Simple and Intuitive
Perfect for anyone new to U.S. tax requirements.
Save Time, No Surprises
Get quick calculations and clear estimates for better tax planning.
Detailed Results
Based on U.S. tax regulations, results are tailored to your company's structure and state.
Frequently Asked Questions.
Generally yes — the IRS requires a corporation to make estimated payments if it expects to owe $500 or more in federal tax for the year.
For a calendar-year C-Corp, the four installments are due April 15, June 15, September 15, and December 15.
US C-Corps pay a flat 21% federal rate on taxable income. This calculator subtracts any net operating loss carried forward from a prior year first, then applies that rate.
Many smaller corporations can use a “safe harbor” and pay the lower of this year's estimated tax or last year's actual tax to avoid an underpayment penalty — this calculator applies that automatically when you enter a prior-year tax amount.
The same rule applies, just shifted — payments are generally due on the 15th day of the 4th, 6th, 9th, and 12th months of your fiscal year instead.
No — it's a simplified estimate for planning purposes only, and doesn't account for every credit, state tax, or unusual situation. FastLLC's bookkeeping and tax filing service can prepare your exact payments and annual return.
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From formation to taxes to growth — FastLLC is here to guide you.
