How a C corporation is taxed and what it files

How much federal tax does a C corporation pay?

A C corporation pays federal income tax on its own taxable income at a flat 21%. Taxable income is not the same as sales or cash left in the bank: the corporation reports revenue, allowable expenses, deductions, and credits on Form 1120 (IRS: Publication 542; Form 1120 instructions).

The rate applies whether the corporation has one shareholder or many. State taxes and certain separate federal taxes can add to the bill, and credits can reduce it; the flat rate alone does not determine its final payment (IRS: Publication 542). The corporate alternative minimum tax applies only to corporations averaging more than $1 billion a year of adjusted financial statement income over three years (US Code: section 59).

Why is C corporation income taxed twice?

The corporation is a separate taxpayer. It pays tax when it earns a profit; if it later pays that profit as a dividend, the shareholder may pay tax on the dividend. The corporation cannot deduct the dividend (IRS: Forming a corporation).

For an individual shareholder, a dividend may qualify for lower capital gain rates if the stock and holding-period rules are met; otherwise it is taxed as ordinary dividend income. The net investment income tax may also apply above the shareholder's income threshold (IRS: Topic 404; Publication 550; Topic 559). "Earnings and profits" is a tax measure of current and prior corporate profits, not simply cash in the bank. A payment is generally a dividend up to that amount. Any excess can reduce stock basis and then create gain, so check the earnings and profits records before labeling a distribution (IRS: Publication 542).

How do owners take money out: salary or dividends?

An owner who works for a C corporation can receive wages for services and dividends as a shareholder. Wages generally reduce corporate taxable income when deductible, while dividends do not. An officer's wages require withholding and payroll reporting; the amount should match the work performed (IRS: Paying yourself; Form 1120 instructions).

The IRS can treat an unreasonably high owner salary as a distribution. An officer who receives pay for services cannot bypass payroll by calling those payments dividends (IRS: Publication 542; IRS: Paying yourself). Keep payroll records, a description of the owner's work, and the decision to pay any dividend.

What if I take money or pay personal costs through the corporation?

Money taken from a C corporation needs a real classification: wages, a dividend or other distribution, repayment of an owner's advance, or a genuine loan. Paying an owner's personal bill does not make it a business expense. The IRS may treat the benefit as a taxable distribution even if no dividend was declared (IRS: Topic 404; Publication 542).

Loans to owners need more than a ledger label. The IRS describes an arm's-length loan as having a contract, stated interest, a repayment period, and consequences for nonpayment. Below-market interest can itself be treated as a distribution or other payment. Canceled debt, property transferred for less than fair value, excessive rent paid to an owner, and excessive salary can also become constructive distributions (IRS: Paying yourself; Publication 542). Keep the loan agreement, repayments, receipts, and business purpose before preparing the return.

Can the corporation keep its profits instead of paying dividends?

Yes. The corporation pays tax on taxable profit when earned, even if it keeps the cash. Shareholders generally pay dividend tax when that profit is distributed, not while the corporation retains it (IRS: Forming a corporation). The corporation can retain earnings for expansion, working capital, or another genuine business need. But retaining earnings to avoid shareholder income tax can trigger a separate accumulated earnings tax of 20% on the amount defined by the tax law, after its accumulated earnings credit (IRS: Publication 542; US Code: sections 531–532).

Prior accumulated earnings and profits reduce these minimum-credit amounts. They are not a cap on cash the corporation may keep. The tax depends on the reason for the accumulation and the statutory calculation; document specific planned uses of retained funds (US Code: section 535). A closely held corporation with mostly passive income may also owe the separate 20% personal holding company tax on undistributed income and file Schedule PH. Fees from a contract that names the owner doing the work, or lets the client pick that person, also count when that owner holds 25% or more of the stock by value (IRS: Schedule PH instructions).

What happens when the corporation loses money?

A C corporation's business loss stays with the corporation; its shareholders cannot deduct that loss on their personal returns. A qualifying net operating loss can be carried forward to later years, with no time limit for losses arising under current rules; only farming and certain insurance company losses can be carried back (IRS: Forming a corporation; Form 1120 instructions).

For losses arising under current rules, the net operating loss deduction is generally limited to 80% of the later year's taxable income, with exceptions and different treatment for older losses. A corporation's capital loss is different: it offsets only capital gains, not operating income, and is carried back three years, then forward up to five (US Code: section 172; IRS: Publication 542). An ownership change (generally, shareholders holding at least 5% of the stock raising their combined stake by more than 50 percentage points within three years) limits how much older loss can offset income each year (Form 1120 instructions; US Code: section 382). Preserve prior returns and loss schedules, especially before selling shares or bringing in investors.

What does a C corporation file, and when is it due?

A domestic C corporation generally files Form 1120 for each tax year, including a year with no taxable income. A calendar-year corporation generally files by April 15; another year-end normally uses the 15th day of the fourth month after year-end. The former third-month rule for a June year-end applies only to tax years beginning before 2026; a short year ending in June is treated as ending June 30 for this rule. For a new corporation's short first year or a dissolved corporation's final return, count from the end of the short period or the dissolution date (Form 1120 instructions). A weekend or legal holiday moves the due date to the next business day (IRS: Publication 509; Public Law 114-41, section 2006).

Form 7004 extends filing time, not payment time (IRS: Form 1120 instructions). The IRS lists payroll and dividend forms separately from Form 1120 (IRS: Forming a corporation; Publication 542). For an inactive corporation or a full state-by-state filing check, see Which returns your business files. Dividends to foreign persons may instead require withholding and Forms 1042 and 1042-S; Foreign-owned C corporation filing covers foreign-owner reporting, including possible Form 5472 (IRS: Publication 515).

Does a C corporation have to pay estimated tax?

A C corporation generally makes federal estimated tax payments if it expects tax after credits of at least $500. Installments fall on the 15th day of the fourth, sixth, ninth, and twelfth months of its tax year, moved to the next business day for a weekend or legal holiday (IRS: Form 1120 instructions).

The corporation must make estimated-tax installments by electronic funds transfer (IRS: Form 1120 instructions). It generally calculates installments from current-year tax or, if eligible, last year's tax. The prior-year method requires a full prior tax year with positive tax. A large corporation (taxable income of $1 million or more in any of the three prior years) can use that method only for its first installment. With seasonal or uneven income, the annualized income or adjusted seasonal installment method may lower installments; the corporation then attaches Form 2220. Form 2220 helps determine an underpayment penalty; earlier short payments can matter even if the final return is paid in full (IRS: Publication 542; Form 2220 instructions).

What state taxes does a C corporation pay?

State obligations depend on where the corporation is incorporated, registered, earns income, and does business. Federal Form 1120 does not replace state returns, franchise taxes, or state estimated payments. A corporation operating across states may need to divide taxable activity among them under each state's rules.

For a California minimum tax question, see California minimum tax and LLC fee. For a Delaware bill, see Delaware franchise tax. Gather incorporation and registration records, where employees work, and sales by state to identify other filing obligations.

Example

Illustrative amounts in US dollars; the example ignores state tax, credits, and owner payroll. A C corporation has $100,000 of taxable income and pays $21,000 of federal corporate income tax at 21%. It keeps $39,000 for operations and pays $40,000 as a dividend from earnings and profits. The dividend does not reduce the corporation's $100,000 taxable income. If the shareholder's federal tax on that dividend were $6,000, the corporation and shareholder would pay $27,000 combined ($21,000 plus $6,000). The shareholder's actual tax depends on their income, whether the dividend qualifies for lower rates, and any net investment income tax.

Different for you?

• Choosing an entity or planning a share sale: LLC or C corporation covers the structure choice and section 1202.
• Considering an S election: Should you elect S corporation status? covers that separate tax treatment.
• A foreign owner or cross-border payments: Foreign-owned C corporation filing covers additional reporting.
• A Delaware or California bill: use the Delaware franchise tax or California minimum tax guide.
• A missed return or payment: Late filing and payment penalties covers the consequences and relief rules.
• Owner loans, retained profits, losses, or filings across states: bring prior Forms 1120, payroll records, shareholder loan documents, distribution records, loss schedules, and state activity records to tax preparation.