Once you enter all this via the Interview, TT will do the calculations. Here are some Tax Planning tools
Since you are using the Desktop software, there is a What-if worksheet. Go to Forms Mode, click Forms in the upper right (left for Mac). Then click Open Forms box in the top of the column on the left. Open the US listing of forms and towards the bottom find the What-if worksheet.
Or you can copy your file with another name and test in the copy. Go to FILE-SAVE AS.
