Citibank paid me interest on two bank accounts but withheld taxes on the interest paid. I have been able to enter the interest income. Where do I enter the taxes paid?

There is an entry in the interest income section to report Federal taxes withheld from interest income reported on Form 1099-INT.  

To see that field so that you can input the information, check the box that says 'my form has info in more than just box 1' or 'my form has info in other boxes'.  This will expand your screen to allow other inputs such as box 4, Federal income tax withheld.

Use these steps to go back to the interest income section of your return:

• On the top row of the TurboTax online screen, click on Search (or for CD/downloaded TurboTax locate the search box in the upper right corner)
• This opens a box where you can type in “interest income” (be sure to enter exactly as shown here) and click the magnifying glass (or for CD/downloaded TurboTax, click Find)
• The search results will give you an option to “Jump to interest income”
• Click on the blue “Jump to interest income” link