DG Thompson, founded in 1987, is Australia's largest and oldest legal costing firm as a consequence of acquisition and expansion.

In May 2004 Australia's then largest legal costing firm DG Thompson, acquired Sydney's oldest legal costing firm Driscoll Matters + McDonald. The company was then renamed DG Thompson Driscoll + Matters and became an incoporated legal practice.

In April 2005 the Company acquired Queensland’s oldest firm of costs consultants, Monsour Legal Costs.

July 2005 saw the opening the the Company's Canberra office.

In October 2006, the Company returned to the DG Thompson name.