New Topsoil Covering?

by EJ
(Kansas City, MO)

I have a large, 30'x20', low spot in the back yard next to the house that I want to fill in with topsoil. We'll slope the topsoil away from the house so that it's roughly 12" thick at the house, tapering off into the yard.

I have to decide the best way to cover the new topsoil. Its late fall right now, the trees have lost most of their leaves, and the grass is still green. I live in central Missouri. Will it be better to remove the existing sod so it can be used to cover the new topsoil (I've never run a sod cutter) or should I buy new sod and lay it over the top of the new soil. Would it be better to forego sodding altogether and simply sow seed and cover it with hay for the winter?