Form 1120 reports a C corporation's income, deductions, credits, and federal tax. Learn deadlines, double taxation, records, and California rules.
Form 1120, U.S. Corporation Income Tax Return, is the federal return domestic C corporations use to report income, gains, losses, deductions, and credits and calculate corporate income-tax liability. Unlike a partnership filing Form 1065, a C corporation is generally a separate federal taxpayer that pays tax on its own taxable income.
Form 1120 is not the return for every business with "Inc." or "LLC" in its name. A corporation with a valid S election generally files Form 1120-S, while an LLC's federal return depends on its ownership and classification election.
Most domestic corporations must file Form 1120 whether or not they have taxable income, unless they are required or permitted to file a special return. An eligible entity that elected to be taxed as a corporation may also file it.
Specialized entities — including S corporations, foreign corporations, exempt organizations, life insurance companies, and certain cooperatives — use different forms. A new corporation should verify its classification and any election acceptance rather than assuming its intended status controls.
The return generally reports gross receipts, returns and allowances, cost of goods sold, dividends, interest, rents, capital gains, and other income. It then reports deductions such as compensation, repairs, bad debts, rent, taxes, interest, charitable contributions, depreciation, employee benefits, and other ordinary and necessary business expenses.
Supporting schedules may include:
Assume a corporation has $500,000 of taxable revenue and $400,000 of allowable deductions after book-to-tax adjustments:
| Item | Amount |
|---|---|
| Taxable revenue | $500,000 |
| Allowable deductions | ($400,000) |
| Federal taxable income | $100,000 |
| Federal corporate tax at 21% | $21,000 |
This simplified example excludes credits, special taxes, net operating losses, estimated payments, and other adjustments. The 21% federal corporate rate applies to taxable income under current law, but the final balance due is tax liability minus credits and payments — not merely 21% of book profit.
A C corporation may experience two levels of tax. First, the corporation pays tax on its income. If it later distributes after-tax earnings as a dividend, the shareholder may also pay tax on the dividend.
A cash transfer to a shareholder is not automatically deductible compensation. It may be wages, a dividend, loan repayment, return of capital, reimbursement, or another transaction. The corporation should document the purpose and use consistent payroll, loan, and board records. Excessive or unreasonable compensation can also be challenged.
A calendar-year C corporation generally files Form 1120 by the 15th day of the fourth month after year-end, normally April 15. A corporation with a June 30 fiscal year generally has a different statutory schedule. Weekend and holiday rules can move the exact date.
Form 7004 can generally extend the filing deadline, but not the time to pay. Corporations usually make estimated tax payments during the year when expected tax reaches the applicable threshold. A corporation should distinguish return preparation, extension payment, estimated installments, and the final balance due.
Form 1120 calculates tax for a C corporation. Form 1065 reports partnership items that generally pass through to partners. Form 1120-S reports an S corporation and passes many items through to shareholders on Schedule K-1, although an S corporation can owe certain entity-level taxes.
Losses also differ. A C corporation's net operating loss remains at the corporate level; shareholders generally do not deduct the corporation's operating loss on their personal returns. Partnership and S corporation losses may pass through, but are subject to basis and other limitations.
A C corporation incorporated, registered, doing business, or receiving California-source income generally files California Form 100. California's general C corporation tax rate is 8.84% for corporations other than banks and financial institutions, and an $800 minimum franchise tax generally applies.
California does not conform to every federal deduction, depreciation provision, credit, or net-operating-loss rule. A corporation may need a separate California depreciation schedule, apportionment calculations, and state book-to-tax adjustments. The federal Form 1120 should not be treated as a complete California return. Year-end close should include reconciliation of book income, federal taxable income, and California income separately.
Heath Income Tax helps California corporations coordinate bookkeeping, payroll, estimated payments, shareholder transactions, and federal and California business returns.
Does an inactive corporation still file?
Often yes. Federal and California filing duties can continue until the entity and its tax accounts are properly closed.
Can an LLC file Form 1120?
Yes, if it is classified or elects to be classified as a corporation and is not filing as an S corporation.
Is Form 1120 the owner's personal return?
No. The corporation files separately. Owners still report wages, dividends, gains, or other personal items on their own returns.
Does a loss create a shareholder deduction?
Generally not for a C corporation. The loss remains with the corporation, subject to corporate net-operating-loss rules.
The definitions and examples on this page are for informational purposes only and do not constitute tax advice. Tax laws change frequently and individual circumstances vary. Consult a qualified tax professional before making decisions based on this content.
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