New Congressional Budget Office Director Keith Hall on Wednesday outlined how his office plans to implement new rules requiring that the economic effects of selected legislation be considered when making budget estimates — a key change that Republicans have fought for for decades.

Historically, the CBO has evaluated legislation on what’s known as a static basis. So, for instance, if a piece of legislation cuts taxes, the CBO only calculated the amount of money in lost revenue — rather than for accounting for the fact that if tax cuts spur economic growth, some of that lost revenue would be recouped. Conversely, tax hikes could shrink the economy, and offset at least some revenue gains.