Complex sentence: Incidentally, and more so now than ever, owners and contractors use retainage as a source of financing for the project, contractors in turn withold retainage from subcontractors, frequently at a greater percentage then is being withheld from them.
Split into simpler sentences: Incidentally, and more so now than ever, owners and contractors use retainage as a source of financing for the project. Contractors in turn withold retainage from subcontractors, frequently at a greater percentage then is being withheld from them.