By James Philip 
Fig 1
Firstly, create your top surface using any of the methods available. As in Fig 1
Once the surface has been created select it and in the properties palette change it’s phasing to existing. See Fig 2
Fig 2
Navigate to the Massing and Site tab and choose graded region. Choose the first option which duplicates the surface and adds it to the phase New Construction. See Fig 3
Fig 3
You now add your land fill changes to this new surface, either by adding a building pad and/or editing the surface elevation points. See Fig 4
Fig 4
Once the editing is complete select the surface and at the bottom of the properties palette in the Other category, the Cut, Fill and Net Cut/Fill values are displayed. See Fig 5
Fig 5
If the height of the Building pad is altered, then to update the cut and fill values. Select the toposurface, chose the edit surface button on the ribbon. Using the place points command, set the elevation to the height of the toposurface and place lots of points evenly placed around the perimeter of the Building Pad and accept the update by selecting finish surface button. See Fig 6
Fig 6
Please Note:
The values given can be inaccurate ( to 2%) and should only be used for an approximate indication of Cut and Fill values.