Over the last decade or so, a relatively small but growing number of national revenue agencies have sought to better understand the health of their tax system by turning their attention to the concept of the ‘tax gap’— the difference between the estimated amount of tax legally payable for...

Historically, national revenue agencies have relied largely on trends in aggregate revenue collections along with reporting on compliance yields as the central element of their performance reporting, together with a few efficiency-related measures. Generally, trends of increasing revenue...