As of February 2015, individual sections of the Federal Tax booklet can be found under the forms and publications section of the official Internal Revenue Service website. The current list of forms is prefaced with a set of prefaced documents for both individuals and businesses, complete with instructions.
Some of the featured forms on the IRS.gov website include Form 1040 and its various related forms, such as the 1040-ES which covers estimated tax on income. The business portion of the online tax forms include the W-4, which is the employee's withholding allowance certificate. A related form is the W-2, which is a statement of how much wages the business pays out.