I have a wall in my basement in which I have plumbing (water & sewer pipes) than run about 8" off of the concrete wall.

I want to frame a wall in front of these, which will make the wall approx. 12" offset forward of the basement concrete wall.

My question is how do I create firestopping (10' ceilings) in that false wall, when it is 12" offset?

How do I do this? Any ideas out there?

You install a layer of drywall to the ceiling that goes out the distance of the offset prior to building the wall. Screw the new wall top plate to the ceiling joists through the drywall and you are all done.

perfect, thanks for the advice...

Just to be clear you put up strips of drywall, you don't need to drywall the entire ceiling. First you snap a chalk line on the joists (or blocking) and install drywall out to that line. then when you put up the wall use the edge of the drywall strips as a reference line for getting the wall straight.