You don't need to show how much is taxes as TurboTax will do this for you.
The amount taxed will depend on all the other income that is reported on the return.
I would enter all that income and then if you want to see how TurboTax computed this for you go to:
View in upper left
then in the drop-down select Forms
select the Social Security Benefits Worksheet, and this will show you the detail.
This is one reason you buy the Program so it does this computations for you .
TurboTax has a 100% accuracy guarantee.