Corporate income tax is a tax on the profit a business makes

A corporate income tax is a tax that a business pays to the federal government and usually to state and local governments too, based on how much money the business earned after subtracting its costs. If a company brings in $1 million in revenue but spends $700,000 running the business, it pays tax on the remaining $300,000 — not on the full $1 million. The tax rate varies by state and has changed at the federal level over time, so the actual amount a business owes depends on where it operates and what year it is.

Not all businesses pay corporate income tax the same way. A large corporation structured as a C corporation pays tax on its profits directly. A small business structured as an S corporation, partnership, or sole proprietorship often does not pay corporate income tax at all — instead, the owners report the business income on their personal tax returns. This difference in how businesses are taxed is one reason business owners choose one structure over another.

Key Takeaways

  • Corporate income tax is calculated on a business's profit after deducting operating costs, not on total revenue.
  • The federal corporate income tax rate is a flat percentage, while state and local rates vary by location and can range from zero to over 12 percent.
  • Only certain business structures, mainly C corporations, pay corporate income tax directly; other structures pass income to owners' personal returns.
  • Businesses can reduce their taxable income by deducting legitimate business expenses like salaries, rent, equipment, and supplies.

How the federal corporate income tax rate works

The federal government taxes corporate profits at a single flat rate. As of 2024, that rate is 21 percent on corporate profits. This means if a corporation has $1 million in taxable profit after deductions, it owes the federal government $210,000. This rate was set by the Tax Cuts and Jobs Act in 2017 and has remained the same since then.

Before 2017, the federal corporate tax rate was higher and used a tiered system where different portions of profit were taxed at different rates. The shift to a flat 21 percent rate was intended to simplify the system and make U.S. corporate taxes more competitive with other countries. However, Congress can change this rate at any time through new legislation.

State and local corporate income taxes vary widely

On top of federal tax, most states also tax corporate profits. State corporate income tax rates range from zero percent in states like Nevada, South Dakota, and Texas to over 12 percent in states like Iowa and New Jersey. Some states have no corporate income tax at all, while others have rates that fall somewhere in the middle — typically between 5 and 9 percent.

A few cities and counties also impose their own corporate income taxes or gross receipts taxes, which are taxes on total revenue rather than profit. This means a business operating in multiple states or cities may owe different tax rates in each location. A company with headquarters in New York and a branch in Texas, for example, would owe New York's corporate tax on profits from New York operations but would owe nothing to Texas on Texas profits since Texas has no corporate income tax.

What counts as profit for corporate tax purposes

Corporate profit is not the same as revenue. A business starts with all the money it brings in, then subtracts every legitimate business expense. These deductions include employee salaries and benefits, rent or mortgage on office and factory space, utilities, equipment purchases, supplies, insurance, interest on business loans, and depreciation on assets like machinery and vehicles.

The goal of these deductions is to tax only the money the business actually keeps, not the money that flows through it. A restaurant that brings in $500,000 in sales but spends $350,000 on food, labor, rent, and utilities has only $150,000 in taxable profit. The deductions are what make the difference between a company's gross revenue and its taxable income.

The difference between corporate and personal income tax

Corporate income tax and personal income tax are separate systems. When a C corporation pays corporate income tax on its profits, the owners do not pay personal income tax on those same profits — at least not yet. However, when the corporation distributes profits to shareholders as dividends, those shareholders then pay personal income tax on the dividends they receive. This creates what some call "double taxation" because the same money is taxed twice: once at the corporate level and once at the personal level.

Other business structures avoid this double taxation. If you own a sole proprietorship, partnership, or S corporation, the business itself does not pay income tax. Instead, you report all the business income on your personal tax return and pay personal income tax on it. This is why many small business owners choose these structures — they pay tax only once, at the personal level, rather than at both the corporate and personal levels.

Why businesses use deductions to lower their taxable income

Every dollar a business can deduct from its revenue reduces the amount of profit it owes tax on. If a company can deduct $50,000 more in legitimate business expenses, it reduces its taxable profit by $50,000. At the federal rate of 21 percent, that $50,000 deduction saves the company $10,500 in federal tax alone. This is why businesses keep careful records of all their expenses and why tax planning is a significant part of business accounting.

However, deductions must be for real business expenses. The IRS does not allow deductions for personal expenses, even if the owner tries to claim them as business costs. A business owner cannot deduct a personal vacation as a business trip or a personal car as a business vehicle unless it is genuinely used for business purposes. The line between legitimate and illegitimate deductions is where many disputes between businesses and the IRS occur.

How corporate tax affects business decisions

Corporate tax rates influence where businesses choose to operate and how they structure themselves. A company considering whether to open a new office might compare the corporate tax rates in different states and choose the state with lower taxes, all else being equal. Similarly, a business owner deciding whether to incorporate as a C corporation or an S corporation will consider the tax consequences of each choice.

Tax also affects how much profit a business can reinvest in growth. If a company owes 30 percent of its profit in combined federal, state, and local taxes, it has only 70 percent left to spend on new equipment, hiring, or expansion. This is one reason business groups sometimes argue that lower corporate tax rates encourage investment and job creation, though economists debate how much of an effect tax rates actually have on business behavior.

Frequently Asked Questions

Do all businesses pay corporate income tax?

No. Only C corporations pay corporate income tax directly. Sole proprietorships, partnerships, S corporations, and LLCs typically do not pay corporate income tax. Instead, the business income passes through to the owners' personal tax returns, where they pay personal income tax on it. The business structure determines whether corporate income tax applies.

What is the difference between corporate income tax and payroll tax?

Corporate income tax is based on a business's profit. Payroll tax is based on employee wages and is paid by both the employer and employee to fund Social Security and Medicare. A business pays both: payroll tax on every dollar of employee wages, and corporate income tax on its profit after all expenses, including those wages, are deducted.

Can a business pay zero corporate income tax even if it is profitable?

Yes, if it uses deductions and credits to reduce its taxable income to zero or below. A business might have a profitable year but still owe no federal corporate income tax if it has large deductions, carries forward losses from previous years, or uses tax credits. However, some states have minimum taxes that explore even when taxable income is zero.

Why did the federal corporate tax rate change to 21 percent?

The Tax Cuts and Jobs Act, passed in 2017, lowered the federal corporate tax rate from a tiered system (with rates up to 35 percent) to a flat 21 percent. The stated goal was to simplify the tax code and make U.S. corporate taxes more competitive internationally. Congress can change this rate again through new legislation.

How do multinational corporations handle corporate income tax?

Multinational corporations must pay corporate income tax in each country where they operate, based on the profits they earn in that country. Tax treaties between countries help prevent the same income from being taxed twice. However, how multinational corporations allocate profits across countries is complex and is an area where tax planning and disputes with tax authorities frequently occur.