What is Form 1120?
Form 1120 (U.S. Corporation Income Tax Return) Form 1120 is the annual income tax return for US C-corporations. For foreign-owned single-member LLCs (disregarded entities), a "pro forma" Form 1120 is filed alongside Form 5472 as an information return — no tax is typically owed since the entity is disregarded.
| Detail | Information |
|---|---|
| Official Name | U.S. Corporation Income Tax Return |
| Filing Deadline | April 15 for calendar-year corporations (15th day of the 4th month after fiscal year end). 6-month extension available via Form 7004. |
| Penalty for Non-Filing | 5% of unpaid tax per month (up to 25%) for late filing. For pro forma returns filed with Form 5472, the $25,000 penalty under IRC §6038A applies. |
| Filed With | IRS |
Who Needs to File Form 1120?
US C-corporations, foreign-owned single-member LLCs filing a pro forma 1120 (with Form 5472), and entities that elected C-corporation tax treatment via Form 8832.
Non-Resident Relevance
If you are a non-resident entrepreneur with a US LLC or US-source income, Form 1120 may be a critical part of your US tax compliance. Consult with a qualified tax professional to determine if this form applies to your situation.
Filing Deadline
April 15 for calendar-year corporations (15th day of the 4th month after fiscal year end). 6-month extension available via Form 7004.
Filing on time is critical. If you need more time, file Form 7004 for an automatic 6-month extension before the original due date. Note that an extension of time to file is not an extension of time to pay.
Penalties for Non-Compliance
Penalty Warning
5% of unpaid tax per month (up to 25%) for late filing. For pro forma returns filed with Form 5472, the $25,000 penalty under IRC §6038A applies.
The IRS enforces these penalties strictly, especially for information returns related to foreign-owned entities. In many cases, there is no reasonable cause exception, making timely filing essential.
How to Complete Form 1120
Here is a section-by-section breakdown of Form 1120:
Header / Entity Info
Corporation name, address, EIN, date of incorporation, and total assets.
Income (Lines 1-11)
Gross receipts, cost of goods sold, dividends, interest, rents, royalties, and other income. For pro forma returns, most lines will be zero.
Deductions (Lines 12-29)
Compensation, rents, taxes, interest, depreciation, and other deductions.
Tax and Payments (Lines 30-36)
Taxable income, tax computation, credits, and payments. The current corporate tax rate is 21% flat.
Schedule L – Balance Sheet
Assets, liabilities, and equity at the beginning and end of the tax year.
Schedule M-1 / M-2
Reconciliation of income per books with income per return, and analysis of unappropriated retained earnings.
Filing Tip
Given the complexity and steep penalties associated with Form 1120, we strongly recommend working with a qualified tax professional who has experience with non-resident tax filings. Errors or omissions can trigger significant penalties.
Common Mistakes to Avoid
These are the most frequent errors we see when clients attempt to file Form 1120 on their own:
- Not filing a pro forma 1120 with Form 5472 for disregarded entities
- Forgetting to check the "initial return" box on the first filing
- Not including Schedule L balance sheet for the LLC
- Using the wrong tax year or period
- Filing Form 1120-F instead of 1120 for a domestic LLC owned by a foreigner
Need Help Filing Form 1120?
Our tax experts specialize in preparing and filing Form 1120 for non-resident entrepreneurs. Avoid costly penalties — let us handle it.
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