What is Form 1120 in the USA?

One useful way to think about it is:

Form 1120 = C corporation federal income tax return.

Form 1120-S = S corporation federal income tax return.

The distinction isn't based simply on whether the business is an LLC, small business, or large company. The federal tax classification matters.

Also, don't confuse Form 1120 with an individual income tax return such as Form 1040. A corporation is a separate taxpayer for federal income tax purposes when it is taxed as a C corporation.

If you're an owner of the corporation, you may have your own individual tax filing obligations as well. The corporation's Form 1120 doesn't automatically replace your personal return.

For a corporation with foreign shareholders, international transactions, or owners living outside the US, there can also be additional reporting considerations. That's an area where I'd be particularly careful about relying on general forum advice.

The IRS instructions are worth checking for the specific tax year because forms and filing requirements can change.

I filed Form 1120 for a corporation that had relatively little activity, and one thing that surprised me was that having little or no taxable income doesn't automatically mean there is no filing requirement.

The form is basically the corporation's federal income tax return. It covers the company's financial activity for the tax year and calculates the federal corporate income tax based on the applicable rules.

The form can involve more than just entering revenue. Depending on the company, there can be deductions, credits, balance-sheet information, ownership-related information, and various schedules.

As for Form 1120-S, that's where the corporation's federal tax classification matters. An S corporation generally files Form 1120-S rather than the regular Form 1120.

I'd also pay attention to the tax year. A calendar-year corporation and a corporation using a different fiscal year won't necessarily have the same filing deadline.

If this is your first corporate return, I'd avoid relying on a generic checklist because the required schedules can depend heavily on what the corporation actually did during the year.

Form 1120 is generally the US federal income tax return for C corporations. That's the main distinction that helped me understand it.

It's not simply a form for businesses that made a profit. A corporation can have a filing obligation even if its income is very low or it had a loss. Whether a particular corporation must file depends on its tax classification and circumstances.

Form 1120 reports information about the corporation's income, deductions, taxable income, and federal income tax. There are also schedules and supporting information depending on the corporation's situation.

The 1120-S confusion is common. Form 1120-S is associated with S corporations, which have a different federal tax treatment. So you shouldn't choose between the two just because one seems easier or more appropriate for the company's size.

The corporation's tax election and classification are important.

For the deadline, I wouldn't use a single date for every corporation. The filing deadline depends on the corporation's tax year and other circumstances.

I'd start with the IRS instructions for Form 1120 and confirm the company's federal tax classification before deciding which return applies.

Who should file Form 1120? 

This form is used by American corporations to report their income, gains, and losses.