No matter which filing status you use, the Form 1040, along with its counterparts the 1040EZ and the 1040A, is the main form in which you calculate your income and subtract deductions to determine the actual amount due at tax time. Known commonly as "the long form" the 1040 is only two pages long but contains over 70 different data fields, and is generally accompanied by different supporting forms.
Those who opt to itemize their deductions will list them on a Schedule A, filed in addition to the Form 1040. Deductions such as property taxes, charitable contributions, mortgage interest, state taxes, and medical expenses can reduce your tax-bill significantly, making this form a valuable tax document to itemizers.
Schedule B form applies to taxpayers who have investment income, as it calculates all of the interest and dividends over $1,500 received throughout the year. However, it only applies to interest and dividends that are taxable, so accounts that have tax advantages, like IRAs and 401(k) are exempt, meaning they won't raise your taxable income.
Schedule C tax form is used by freelances and small business owners to document business profit and loss for the tax year. If you contract, consult, or work independently of an employer, you'll use this form to report your income. Additionally, you can use this form to deduct business expenses, such as advertising, home office expenses, supplies, and operating costs.
Traders of stocks, bonds, or other monetary instruments will use a Schedule D to total the amount of capital gains and losses on this form. Most taxpayers have investments that do well throughout the year, and others that don't. Regardless, you need to report all of them to the IRS, as up to $3,000 in capital losses may be deductible.