A domestic C-corporation in the United States pays a flat 21% federal income tax on its taxable profits, and most also owe a state corporate income tax that runs from about 2% up to 11.5% depending on where they operate. That is what corporations pay in taxes on paper. In practice, credits, deductions, and structural choices push the effective rate well below the sum of those two numbers for most large companies, and the size of the gap is often what people are really asking about.
The 21% Federal Rate
The Tax Cuts and Jobs Act of 2017 replaced a graduated bracket system that topped out at 35% with a single flat rate of 21% on every dollar of a corporation’s taxable income.1Office of the Law Revision Counsel. 26 USC 11 – Tax Imposed Unlike many individual provisions of the same law, the 21% corporate rate is permanent. It stays at 21% unless Congress changes it.
Taxable income is not gross revenue. A corporation starts from total receipts, subtracts cost of goods sold, ordinary business expenses, and other allowable deductions, and applies the 21% only to what remains. That is why two companies with identical sales can end up owing very different federal tax.
State Corporate Income Taxes
Most states impose their own corporate income tax on top of the federal 21%. North Carolina sits at the low end with a flat 2%. New Jersey sits at the high end, with a top marginal rate of 11.5% on corporate income above $10 million. Four states have top rates at or above 9%. Roughly a dozen keep top rates at 5% or below.
A few states skip the corporate income tax entirely. South Dakota and Wyoming impose neither a corporate income tax nor a gross receipts tax. Nevada, Ohio, Texas, and Washington use a gross receipts tax instead, which is calculated on total revenue rather than profit. The distinction matters: a gross receipts tax can apply even in a year the company earns no profit at all, because the base is sales, not the bottom line.
The 15% Corporate Minimum Tax on the Largest Companies
Starting in 2023, the Inflation Reduction Act added a second federal layer for the biggest corporations. The Corporate Alternative Minimum Tax imposes a 15% minimum tax on adjusted financial statement income for companies whose average annual book income exceeds $1 billion over a three-year period.2Internal Revenue Service. Corporate Alternative Minimum Tax Adjusted financial statement income begins with the audited net income figure and applies specific adjustments, such as removing federal income taxes and substituting tax depreciation for book depreciation on certain property.3Internal Revenue Service. Instructions for Form 4626
A corporation subject to the CAMT pays the higher of its regular 21% liability or the 15% calculated on adjusted book income. The tax is aimed at companies that report large profits to shareholders but drive their regular tax bill below 15% of that book income through credits and deductions. Small and mid-sized businesses do not hit the $1 billion threshold, so the CAMT is a concern almost entirely for very large multinationals.
Why Effective Rates Are Lower Than 21%
The statutory rate is the number in the law. The effective rate is what a corporation actually pays as a share of its pre-tax profit after every credit, deduction, and exclusion is applied. A Government Accountability Office study of large profitable corporations found that the average federal effective rate came in at roughly 14% of pre-tax book income, well under the statutory rate in effect at the time.4U.S. Government Accountability Office. Corporate Income Tax: Most Large Profitable U.S. Corporations Paid Tax but Effective Tax Rates Differed Significantly from the Statutory Rate
The gap is not evidence of illegal activity. Congress wrote most of these provisions into the tax code deliberately, to encourage specific business behavior. A handful of them do most of the work.
The R&D Credit
Section 41 allows a credit equal to 20% of qualified research expenses above a base amount. Because it is a credit rather than a deduction, it reduces the tax owed dollar for dollar: a $100,000 credit cuts tax by $100,000, while a $100,000 deduction would only cut tax by $21,000.5Office of the Law Revision Counsel. 26 USC 41 – Credit for Increasing Research Activities Technology, pharmaceutical, and manufacturing companies tend to claim the largest amounts.
Depreciation and Immediate Expensing
Equipment, vehicles, and other tangible business property are generally recovered over multiple years through depreciation under the Modified Accelerated Cost Recovery System.6Office of the Law Revision Counsel. 26 USC 168 – Accelerated Cost Recovery System Recent legislation restored 100% bonus depreciation for qualifying property acquired on or after January 20, 2025, so corporations placing qualifying assets in service in 2026 can generally deduct the full cost in the first year.
Section 179 offers a parallel route for smaller purchases. It allows businesses to expense up to $2,560,000 of qualifying asset costs immediately in 2026, with the limit beginning to phase out once total qualifying purchases exceed $4,090,000.7Internal Revenue Service. Rev. Proc. 2025-32 – 2026 Adjusted Items For sport utility vehicles, the Section 179 deduction is capped at $32,000.
Net Operating Losses
A corporation that spends more than it earns generates a net operating loss. Losses arising after 2017 can only be carried forward, and the deduction is capped at 80% of taxable income in any single year, so accumulated losses cannot fully erase a tax bill.8Office of the Law Revision Counsel. 26 USC 172 – Net Operating Loss Deduction The remaining 20% of income stays taxable. Unused losses carry forward indefinitely.
Business Interest Deduction
Corporations can deduct interest on business debt, but Section 163(j) caps the deduction at 30% of adjusted taxable income plus any business interest income. For tax years 2022 through 2024, the calculation excluded depreciation and amortization from the base, tightening the cap for capital-intensive companies. Starting in 2025, recent legislation restored the more favorable formula that adds depreciation and amortization back in, raising the ceiling for many corporations.9Internal Revenue Service. Questions and Answers About the Limitation on the Deduction for Business Interest Expense
How Business Structure Changes the Answer
Not every business pays the 21% corporate rate. The entity type chosen at formation determines whether profits are taxed at the company level, the owner level, or both.
C-Corporations
A C-corporation pays the 21% federal tax on its profits. When after-tax profits are then distributed to shareholders as dividends, shareholders pay tax again on the dividend income at their individual rates. For qualified dividends, individual rates in 2026 are 0%, 15%, or 20% depending on the shareholder’s taxable income. This layered treatment is often called double taxation and is the primary trade-off for the flexibility C-corporations offer in raising capital and holding unlimited shareholders.
S-Corporations and Other Pass-Throughs
S-corporations, partnerships, and most LLCs pay no entity-level federal income tax. Profits and losses pass through to the owners, who report them on personal returns and pay at individual rates. An S-corporation must be domestic, must have no more than 100 shareholders, cannot include nonresident alien shareholders, and is limited to a single class of stock.10Office of the Law Revision Counsel. 26 USC 1361 – S Corporation Defined
A significant change for 2026 is the expiration of the Section 199A qualified business income deduction. From 2018 through 2025, owners of pass-through businesses could deduct up to 20% of their qualified business income before calculating individual tax, effectively lowering the top rate on pass-through income. That deduction is no longer available for tax years beginning after December 31, 2025.11Internal Revenue Service. Qualified Business Income Deduction Pass-through owners now pay individual rates on 100% of their share of business profits, which narrows the gap between pass-through and C-corporation taxation.
Foreign Earnings
U.S. corporations are taxed on worldwide income, not just what they earn at home. The Global Intangible Low-Taxed Income rules, enacted in 2017, require U.S. parent companies to include certain foreign subsidiary income on their domestic return each year, subject to a partial deduction under Section 250. Through 2025 that deduction was 50%, producing an effective GILTI rate of 10.5%. The deduction was scheduled to shrink to 37.5% for 2026 and later years, which would raise the effective rate to roughly 13.125%. Recent legislation may have adjusted these figures, so corporations with significant foreign operations should verify the current rate with their tax advisors.
Separately, the OECD’s Pillar Two framework calls for a 15% minimum effective tax rate in every country where a multinational with at least €750 million in revenue operates. Dozens of countries have begun implementing it. The U.S. has not enacted Pillar Two directly, and it operates country-by-country while GILTI averages across all foreign operations, so U.S. multinationals can face top-up taxes imposed by other countries if their effective rate in a specific jurisdiction falls below 15%.
When the Money Is Due
Corporations generally cannot wait until they file to pay. If expected tax liability for the year is $500 or more, quarterly estimated payments are required on this schedule:12Internal Revenue Service. Estimated Tax
- April 15, covering January through March
- June 15, covering April and May
- September 15, covering June through August
- January 15 of the following year, covering September through December
Underpayment triggers a penalty calculated by applying the federal short-term interest rate plus three percentage points to the underpaid amount for the period it was unpaid.13Office of the Law Revision Counsel. 26 USC 6655 – Failure by Corporation to Pay Estimated Income Tax For the first quarter of 2026, that rate is 7%.14Internal Revenue Service. Quarterly Interest Rates The penalty applies even if the corporation ends up receiving a refund at filing. No penalty applies if the total tax for the year is less than $500.