C Corporation Tax Deadlines: Complete Filing Calendar

C-Corporations face more filing deadlines than almost any other entity type. Between the corporate income tax return, quarterly estimated payments, payroll filings, and information returns, there are over a dozen dates to track each year. Miss one and the penalties add up fast. This guide covers every C-Corp tax deadline for 2026.

Understanding C-Corp Taxation

Unlike S-Corps and LLCs, C-Corporations are separate tax-paying entities. The corporation files its own tax return (Form 1120) and pays taxes at the corporate rate — currently a flat 21% federal rate. When the corporation distributes profits to shareholders as dividends, those dividends are taxed again at the individual level. This is commonly called "double taxation."

Qualified dividends receive favorable tax rates (0%, 15%, or 20% depending on the shareholder's income), which reduces but does not eliminate the double tax. Despite this drawback, C-Corps offer advantages: no restrictions on the number or type of shareholders, the ability to retain earnings at the corporate level, and access to certain deductions not available to pass-through entities.

Form 1120: Corporate Income Tax Return

Due date: April 15, 2026 (for calendar-year C-Corps). This is a change from the historical September 15 deadline — calendar-year C-Corps have filed by April 15 since the PATH Act changes took effect.

Form 1120 reports the corporation's gross income, deductions, credits, and tax liability. It includes schedules for cost of goods sold (Schedule A), dividends and special deductions (Schedule C), compensation of officers (Schedule E), and the balance sheet (Schedule L).

If you need more time, file Form 7004 by April 15 for an automatic 6-month extension to October 15. The extension is for filing only — estimated tax payments are still due on their original schedule.

Quarterly Estimated Tax Payments

C-Corporations must make estimated tax payments if they expect to owe $500 or more in tax for the year. Corporate estimated payments use Form 1120-W as a worksheet and are deposited through EFTPS.

Notice the Q4 deadline is December 15, not January 15 like individual estimated payments. Each payment should be 25% of the estimated annual tax liability. For a detailed look at safe harbor rules and penalty calculations, see our quarterly estimated tax payments guide.

The safe harbor for large corporations (taxable income of $1 million or more in any of the three preceding years) requires paying 100% of the current year's tax. These corporations cannot use the prior-year safe harbor except for Q1.

Payroll Tax Filings

Most C-Corps have employees, which means a full calendar of payroll obligations:

Form 941 — Quarterly Payroll Tax Return

Form 941 reports income tax withheld from employee wages plus the employer and employee shares of Social Security (6.2% each) and Medicare (1.45% each) taxes.

In addition to filing 941, you must deposit payroll taxes on either a monthly or semi-weekly schedule. New employers default to monthly deposits. If you accumulated $100,000 or more in taxes on any day, you must deposit by the next business day.

Form 940 — Annual FUTA Return

Due date: January 31, 2027 (for tax year 2026). Form 940 reports Federal Unemployment Tax (FUTA), which is 6.0% on the first $7,000 of each employee's wages. Most employers receive a 5.4% credit for paying state unemployment taxes, reducing the effective FUTA rate to 0.6%.

FUTA deposits are due quarterly if the cumulative liability exceeds $500. Deposit by the last day of the month following the quarter end.

Information Returns

W-2 — Employee Wage Statements

Due date: January 31, 2026 (for tax year 2025). W-2s must be furnished to employees and filed with the Social Security Administration by January 31. There is no automatic extension for W-2 filing. Late W-2 penalties range from $60 to $330 per form depending on how late they are filed.

1099-NEC — Nonemployee Compensation

Due date: January 31, 2026. File for each independent contractor you paid $600 or more during the year. This form replaced Box 7 of 1099-MISC for reporting nonemployee compensation.

1099-DIV — Dividends and Distributions

Due date: January 31, 2026 (to recipients); February 28, 2026 (paper filing to IRS) or March 31, 2026 (electronic filing to IRS). If your C-Corp paid dividends of $10 or more to any shareholder, you must issue a 1099-DIV. This form reports ordinary dividends, qualified dividends, capital gain distributions, and nondividend distributions.

Complete C-Corp Deadline Calendar for 2026

Penalties for Late C-Corp Filings

Late filing penalties for Form 1120 are calculated as 5% of the unpaid tax per month, up to 25% — the same structure as individual returns. However, the minimum penalty for returns filed more than 60 days late is the lesser of $510 or the full amount of tax owed.

Late estimated tax payments trigger an underpayment penalty at the current federal rate plus 3 percentage points. Large corporations face additional restrictions on using prior-year safe harbor. For a full breakdown of every IRS penalty, read our IRS late filing penalties guide.

C-Corp vs S-Corp: Which Has More Deadlines?

Both structures have similar payroll obligations, but C-Corps have the additional burden of corporate-level estimated tax payments and 1099-DIV filings when distributing dividends. S-Corps file earlier (March 15 vs April 15) but avoid corporate-level taxes entirely. For a side-by-side comparison, see our S-Corp tax deadlines guide.

Frequently Asked Questions

When is the C-Corp tax return due?

Form 1120 is due April 15 for calendar-year C-Corporations. You can file Form 7004 for an automatic 6-month extension to October 15, but estimated tax payments are still due by their original quarterly deadlines.

When are C-Corp estimated tax payments due?

C-Corporation estimated tax payments are due April 15, June 15, September 15, and December 15. Note that the Q4 payment is due in December, not January like individual estimated payments. Estimated payments are required if the corporation expects to owe $500 or more in tax.

What is double taxation for C-Corporations?

Double taxation means C-Corp income is taxed twice: first at the corporate level (21% federal rate on Form 1120), and again at the individual level when profits are distributed as dividends to shareholders. Qualified dividends are taxed at the lower capital gains rate (0%, 15%, or 20% depending on income), which reduces but does not eliminate the double tax.