Taxes Made Simple

These forms are also available from irs.gov. They're just somewhat harder to find there, as you need to know ahead of time the name of the form you want to download.

Forms for People (as opposed to businesses) 

Form 1040 - Instructions - This is your standard form for an individual's tax return.

Form 1040-X - Instructions - Use this form to amend a previously filed return. For instance, if you just learned about some deduction you could have taken last year, you could fill out this form and mail it to the IRS in order to claim the refund you're entitled to as a result of the change.

Forms Specific to Sole Proprietors

Schedule C - Instructions - Use Schedule C (an attachment to your Form 1040) to outline your sole proprietorship's (or single member LLC's) revenue and expenses. Step-by-Step Schedule C Tutorial

Form 1040-ES - Use Form 1040-ES to calculate your estimated tax payments.

Schedule SE - Instructions - Use Schedule SE (also an attachment to your Form 1040) to calculate your Self-Employment tax.

Form 8829 - Instructions - Use this form to calculate your Home Office Deduction. Step-by-Step Form 8829 Tutorial

Forms Specific to Partnerships

Form 1065 - Instructions - The primary form for a partnership's tax return.

Schedule K-1 - Instructions - A Schedule K-1 is filled out for each partner to show his or her share of the partnership's income and expenses. 

Forms Specific to S-Corporations

Form 1120S - Instructions - The primary form for an S-Corporation's tax return.

Schedule K-1 - Instructions - A Schedule K-1 is filled out for each partner to show his or her share of the partnership's income and expenses.

Forms Specific to C-Corporations

Form 1120 - Instructions - The primary form for a C-Corporation's tax return.

Forms for All Businesses

Form 4562 - Instructions - Use this form to calculate your deduction for equipment used in your business (that is, depreciation and/or Section 179 election).

Form 2553 - Instructions - Use this form to elect S-Corp tax treatment for your business.

Forms Specific to Limited Liability Companies (LLCs)