WHAT FORM SHOULD I USE FOR FILING MY BUSINESS TAXES?

Here is a simple reference table that may clear up the confusion:

Type of Business, Tax Liability, Form to Use

Sole proprietor: An unincorporated business that is owned by one individual.

Income Tax, 1040 and Schedule C or C-EZ
Self-employment tax, 1040 and Schedule SE
Estimated tax, 1040-ES

Employment taxes:
State employment taxes, DE-6, DE-7, DE-88
Social Security and Medicare, income and withholding taxes, 941 (943 for farm employees)
Federal unemployment (FUTA) tax, 940 or 940-EZ
Depositing employment taxes, 8190

Excise taxes

Partnership: The relationship existing between two or more persons who join to carry on a trade or business. Each person contributes money, property, labor, or skill, and expects to share in the profits and losses of the business.

Annual return of income, 1065
Employment taxes, same as sole proprietor
Excise taxes

Partner in a partnership (individual)

Income tax, 1040 and Schedule E
Self-employment tax, 1040 and Schedule SE
Estimated tax, 1040-ES

Corporation or S Corporation

Corporation: Prospective shareholders transfer money, property, or both for the Corporation’s capital stock. A Corporation generally takes the same deductions as a sole proprietorship to figure its taxable income, and can take special deductions. The profit of the Corporation is taxed to the Corporation when earned, and then is taxed to the shareholders when distributed as dividends. Shareholders cannot deduct any loss of the Corporation.

S Corporation: An eligible domestic corporation can avoid double taxation by electing to be treated as an S Corporation. In general, an S Corporation is exempt from federal income tax other than tax on certain capital gains and passive income. Shareholders include on their tax returns their share of the Corporation’s separately stated items of income, deduction, loss, and credit, and their share of non-separately stated income or loss.

Income tax, 1120 or 1120-A (corporation), 1120S (S Corporation)
Estimated tax, 1120 or 1120-A (corporation), 1120S (S Corporation)
Employment taxes, same as sole proprietor
Excise taxes

S Corporation Shareholder
Income tax, 1040 and Schedule E
Estimated tax, 1040-ES