Some people already know exactly to the penny the amount they get from the SSA.
If you want to assume that is net after taxes, then you can enter that amount
into the Annual Social Security box.
But then you need to disable the taxes being deducted out.
To do that, click on Settings -> Taxes
and then UNCHECK the box next to the Social Security option.
If you do this the program will NOT try to estimate the taxes owed on Social Security and try to net them out.
It will just use the value you entered directly in the calculations.