IRS Form 1120: U.S. Corporation Income Tax Return (2026)
Form 1120 is the official IRS document used by domestic C-Corporations to report their financial activity, calculate their income tax liability, and claim deductions or credits. Whether your corporation had a banner year or operated at a loss, filing this form is a mandatory step in maintaining your corporate compliance.
Fill Out Form 1120 OnlineWho Must File Form 1120?
Unless specifically exempt, all domestic corporations must file Form 1120. This applies even if your corporation had no taxable income, no gross receipts, or operated entirely at a loss for the 2026 tax year. Note that S-Corporations do not use this form; they file Form 1120-S instead.
What to Have Ready
- Your corporation's Employer Identification Number (EIN)
- Date of incorporation and total assets
- Complete financial statements (Profit & Loss, Balance Sheet)
- Prior year's Form 1120 for reference
- Asset depreciation schedules and payroll records
Detailed Form Walkthrough
Form 1120 is comprehensive, spanning multiple pages and schedules. Here is a breakdown of the core sections you will need to complete:
Basic Information
The top of page 1 requires your corporate identity. You must provide the corporation's legal name, address, and [EIN]. You will also indicate the date the business incorporated and the total assets at the end of the tax year.
Income (Lines 1-11)
This section captures your gross income. You'll report gross receipts or sales, subtract the Cost of Goods Sold (COGS), and add other income sources like dividends, interest, gross rents, royalties, and capital gains. The sum of these lines equals your Total Income.
Deductions (Lines 12-29)
Here, you will detail the expenses incurred to run your business. Common deductions include compensation of officers, employee salaries, repairs, bad debts, rent, taxes, interest, and depreciation. A common error here is miscalculating depreciation; ensure your Schedule 4562 aligns with your entries.
Tax, Refundable Credits, and Payments (Lines 30-36)
After calculating your taxable income (Total Income minus Total Deductions), you will compute your tax owed using Schedule J. You'll then subtract any estimated tax payments or refundable credits to determine if you owe a balance or are due a refund.
Schedules L, M-1, and M-2
For corporations with total receipts and total assets over $250,000, these schedules are mandatory. Schedule L is your balance sheet per your books. Schedule M-1 reconciles your book income with your tax return income (accounting for non-deductible expenses like certain meals or penalties). Schedule M-2 analyzes your unappropriated retained earnings.
Deadlines & Filing Rules
For corporations operating on a calendar year, Form 1120 is typically due by April 15th of the following year. If your corporation uses a fiscal year, the return is due on the 15th day of the fourth month after the end of your tax year.
Always check with the Internal Revenue Service (IRS) for the current year's deadline, as dates can shift due to weekends or holidays.
How to Complete on AmendSign
- Enter Information: Click the fillable fields to type in your corporate data, income, and deductions directly.
- Review & Calculate: Double-check your math and ensure all required schedules (like M-1 or L) are completed if your assets exceed the threshold.
- Sign Electronically: Add a legally binding digital signature for the authorized corporate officer.
- Download & File: Export your finalized Form 1120 as a secure PDF, ready to print and mail or e-file with the IRS.