In this chapter
Common rule: the company files a full Form 1120
A US-organized C corporation generally uses the full Form 1120 to report income, deductions and tax due. The company is a separate taxpayer; its return is separate from its shareholders’ returns. An LLC that effectively elects C corporation treatment follows the applicable corporate rules.
A corporation generally files an income-tax return even without taxable income, subject to exemptions and special rules. Having no profit or not yet taking customer orders does not by itself establish a filing exemption.
Foreign shareholders do not turn a US corporation into a foreign corporation or make it switch to Form 1120-F. Overseas shareholders or customers do not by themselves establish that no corporate return or tax is due.
[12][32][07][12]Separate shareholder and company dealings
- Annual books, bank and platform reconciliations, sales and refunds, expenses, assets and depreciation records.
- Shareholder records, direct and indirect ownership, voting or stock-value changes, and effective dates.
- Shareholder loans, repayments, capital contributions, dividends and related-company agreements, distinguished from one another.
- Payroll, contractor payments, prior payments and returns, IRS correspondence and extension records.
Money received from a shareholder is not automatically revenue; money paid to a shareholder is not automatically a dividend. Establish the transaction and its evidence before choosing the tax treatment.
[12][14][33]Common duties: when the company pays tax
Track the annual return, estimated payments during the year and any final balance separately. A corporation meeting the applicable expected-tax conditions generally makes estimated payments during the year rather than waiting to file Form 1120. Calculate the amounts and dates under the current rules.
For payments to shareholders, first distinguish wages, loan repayments, dividends and other amounts, then check the recipient’s tax and information-reporting requirements. Shareholder receipts do not all receive the same treatment. The additional withholding rules for foreign recipients appear below.
[12][16][17]Foreign-recipient addition: tax withheld from payments
When paying US-source dividends to foreign shareholders, the company may need to withhold part of the payment and send that tax to the IRS on time. Paying the company’s own income tax does not settle this separate withholding question.
Before payment, confirm the recipient’s tax status, beneficial owner and supporting documentation, then determine the withholding treatment and payment deadline. A tax treaty may affect the result, but passport nationality alone does not establish a reduced rate.
Common documentation includes Form W-8BEN for a foreign individual beneficial owner and W-8BEN-E for a foreign entity beneficial owner. Partnerships and intermediaries may need other W-8 forms; one form does not fit every recipient.
Covered payments generally also require Form 1042 annual withholding reporting and Form 1042-S recipient reporting, including recipient copies. A treaty or statutory exemption from actual withholding does not necessarily remove the Form 1042-S requirement. Form 5472 does not replace these returns.
[33][34][35][36]How to submit 1120, 1042 and 1042-S
- 1120: use business-tax software or a preparer. Current rules generally require e-filing if the corporation files ten or more returns of any type during the calendar year, subject to exemptions and waivers. Use the current address rules if paper filing is permitted.
- 1042: electronic filing uses Modernized e-File (MeF). Check the financial-institution, information-return-count and partner-count rules for mandatory e-filing.
- 1042-S: this is a separate information-return process. The 2026 instructions require IRIS for electronic filing of 2026 Forms 1042-S, replacing FIRE. Permitted paper filings use Form 1042-T as required.
Deadlines, payments and separate extensions
Form 1120 is generally due on the 15th day of the fourth month after the tax year ends, with special rules for certain years or situations. Forms 1042/1042-S generally follow the payment calendar year and a March 15 deadline in the next year, adjusted for weekends and holidays.
Corporate estimated payments and withholding deposits can fall due earlier during the year. Applicable Form 1120 or 1042 filing extensions use Form 7004; extensions to file Form 1042-S with the IRS use Form 8809, while recipient-copy extensions have a separate Form 15397 procedure. One extension does not cover every filing, copy or payment.
[12][15][35][36]S corporation status is not automatic
＋What should I check before electing S corporation status?Eligibility, shareholder consent and timing all matter.
General S corporation requirements include domestic status, no more than 100 shareholders, one class of stock and only eligible shareholders. Partnerships, corporations and nonresident alien individuals generally cannot be shareholders. “Nonresident alien” is a tax status, not simply a passport nationality.
Form 2553 makes the S election and has shareholder-consent and timing requirements. An eligible LLC can obtain corporate classification through a valid S election without necessarily filing Form 8832 separately. The two forms are not a mandatory pair.
[09][10]When the IRS has accepted an S election and it remains in effect, the business files Form 1120-S and gives each shareholder a Schedule K-1 showing their share. The business and shareholders still handle their own applicable filing and payment duties.
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