Federal tax forms are available from the Internal Revenue Service website, according to the Gallagher Law Library at the University of Washington School of Law. The IRS Forms & Publications page features the most commonly used forms for individuals and businesses. Forms are searchable by year, topic and number.
As of 2015, Forms W-4, W-9, 1040 and 9465 for individual taxpayers are featured on the Forms & Publications page, according to the IRS. Taxpayers who meet certain criteria can use Form 1040 to file their tax return, and taxpayers who owe taxes can use Form 9465 to request an installment agreement. Taxpayers use Form W-4 to determine the amount withheld from their wages, and the forms page also links to a withholding calculator. Form W-9 allows taxpayers to request a taxpayer identification number.
Also featured on the Forms & Publications page is Form 941 for an employer's quarterly tax return and Form 1099-MISC for contractors, notes the IRS. These and other business forms include instructions and links to related forms. There are also links to forms for tax years as far back as 1916.
State tax forms are available through state government agencies, according to the Federation of Tax Administrators. The organization links to the designated tax agency for each state, and some of these agencies list some or all of their tax forms online.