Governments have resource impacts on the economy and society in many ways. While taxation and direct expenditure impacts have been studied and form the basis of much of the fiscal impact assessments of government, the issue of tax expenditures has been largely ignored. Tax expenditures (concessions granted to individuals and companies) have existed since the early C2oth but were really only acknowledged and counted since the early 1980s. The impacts of tax expenditures are not widely reported or known - although there is a technical economic literature (largely driven by the US) which has attempted to define and classify them. In Australia and Canada these measures (as revenue foregone) are substantial and yet they do not go through any semblance of a budgetary process. Central economic or budgetary agencies can review tax expenditures at any time but they often do not chose to re-open these concessionary schemes. This paper assesses what we know about the scale and scope of tax expenditures in Australia and Canada and attempts to ask whether a more robust 'budgeting' of these measures is possible.