Here are some links to US Tax Records online by state:

Alabama Tax Records online

Alaska Tax Records online

Arizona Tax Records online

Arkansas Tax Records online

California Tax Records online

Colorado Tax Records online

Connecticut Tax Records online

Delaware Tax Records online

DC Tax Records online

Florida Tax Records online

Georgia Tax Records online

Hawaii Tax Records online

Idaho Tax Records online

Illinois Tax Records online

Indiana Tax Records online

Iowa Tax Records online

Kansas Tax Records online

Kentucky Tax Records online

Louisiana Tax Records online

Maine Tax Records online

Maryland Tax Records online

Massachusetts Tax Records online

Michigan Tax Records online

Minnesota Tax Records online

Mississippi Tax Records online

Missouri Tax Records online

Montana Tax Records online

Nebraska Tax Records online

Nevada Tax Records online

New Hampshire Tax Records online

New Jersey Tax Records online

New Mexico Tax Records online

New York Tax Records online

North Carolina Tax Records online

North Dakota Tax Records online

Ohio Tax Records online

Oklahoma Tax Records online

Oregon Tax Records online

Pennsylvania Tax Records online

Rhode Island Tax Records online

South Carolina Tax Records online

South Dakota Tax Records online

Tennessee Tax Records online

Texas Tax Records online

Utah Tax Records online

Vermont Tax Records online

Virginia Tax Records online

Washington Tax Records online

West Virginia Tax Records online

Wisconsin Tax Records online and Voter Records online

Wyoming Tax Records, Voters, Pensions, etc online