1040.com
Here you can find federal and state tax forms.
AARP Tax-Aide
“AARP Tax-Aide is the nation’s largest free, volunteer-run tax assistance and preparation service available to taxpayers with low and moderate income, with special attention to those age 60 and older.”
Internal Revenue Service
Includes forms, publications, withholding calculator, check your refund, find an authorized e-file provider (for individuals), and more.
Sales Tax Clearinghouse
States sales tax rates and combined average city and county rates. You can also search by ZIP code, city, and county.