Box 3 is a reference to the special treatment accorded to interest payments from the United States Treasury. Interest on federal government bonds, bills, and notes is not taxed by the several states.
When entering this interest into TurboTax, enter the name of the payer and the amount, then check the box next to the phrase "What if my form has other boxes filled in?" This will open a screen with Boxes 1 through 14. Your previously entered amount is displayed in Box 1, and should remain there. Then, enter the amount of U.S. Treasury interest in Box 3. Click Continue.
