For individual transcript requests (Form 1040 series, Form W-2, and Form 1099), mail your form to the address below that corresponds with your state. For business transcript requests, send your Form 4506-T to the address assigned for your state.
Use Form 1120, U.S. Corporation Income Tax Return, to report the income, gains, losses, deductions, credits, and to figure the income tax liability of a corporation.
The IRS instructions say that all corporations must file Form 4626, unless they fall under one of four exclusions, to determine whether they are an applicable corporation, and, if so, to calculate the tax.
You can send Form 9465 with the e-return, but the IRS must still approve the installment agreement form.
The difference is that Form 1120 is used by C corporations (C corps), which are liable for corporate federal taxes, and Form 1120-S is used exclusively by S corps.
About Form 1120, U.S. Corporation Income Tax Return. Internal Revenue Service.
An LLC that chooses to be treated as a C corporation for tax purposes is required to file Form 1120 (U.S. Corporation Income Tax Return). If the LLC elects to be treated as an S corporation, Form 1120S (U.S. Income Tax Return for an S Corporation) should be filed instead.