What Is a Form 1120? Definition and Use

Definition

Form 1120 - Form 1120 is the US corporate income tax return, filed by C corporations and by LLCs electing C-corp taxation; a pro-forma 1120 also accompanies Form 5472 for foreign-owned single-member LLCs.

Form 1120 has two distinct uses that confuse many owners. First, an LLC that elects C-corp treatment files a full Form 1120 and pays corporate income tax on its profits. Second, a foreign-owned single-member LLC, which is a disregarded entity owing no corporate tax, still files a pro-forma Form 1120 as a cover sheet for Form 5472, the information return reporting transactions between the LLC and its foreign owner.

The common error is a non-resident owner assuming that disregarded means no filing, then skipping the pro-forma 1120 and 5472 combination entirely. That mistake is expensive: failure to file Form 5472 carries a $25,000 penalty. The pro-forma 1120 in this context is not a tax computation; it is a nearly blank return carrying identifying information so the 5472 attaches to a valid federal filing.

Neither use of Form 1120 touches anonymity, since both are federal filings that never reach the public state record. For Anonymousllc.co customers in Wyoming, New Mexico, Delaware, and Nevada, the pro-forma 1120 plus Form 5472 package is the standard annual compliance deliverable for a foreign-owned disregarded LLC, and Anonymousllc.co flags this obligation for every non-resident single-member client so the filing is never missed.