It seems like you understand the Form 1099-DIV data entry process pretty well already. Boxes 10 and 11 are for municipal (tax-exempt) bonds, and private activity bonds (a sub-set of municipal bonds).
After your main entry screen in TurboTax, however, you are given the opportunity to enter certain additional information, such as US government interest. (Please see the screen-capture image below; simply click to open.) Typically, such federal government interest would come from holding a mutual fund or ETF that invests some (or all) of its assets in US government securities, and then pays you "dividends" as an investor in that fund.
This bring us back to your original question, and the way that you would have to determine that number. Basically, you have to look to your brokerage firm's 1099-DIV statement, which may have a breakout of some kind, for US government interest, and that will be the (percentage) figure you would use to figure out the amount of your dividends that were, in fact, federal interest.
If your brokerage firm hasn't done the legwork for you, then you'd need to do it yourself. Essentially this will involve looking at the website for fund company that sponsors each of your investments (Vanguard, Fidelity, Pimco, etc.), and then accessing their taxpayer information webpage(s). Typically, they will have a federal interest breakdown shown there, by fund.
If you have further
questions, encounter any difficulties, or just want to speak with a live tax
expert who can walk you through your TurboTax entries (including the ability to
screen-share with your computer), please feel free to contact us. We
would be happy to help you (and as a Premier customer, the call is free to
you). Here is a link where you can create a support ticket and reach us:
https://support.turbotax.intuit.com/contact/
Thank you for asking this question.
