The World Bank relies in part on economic benefit estimates to evaluate the merits of investment projects. Recent lending operations for revenue administrations in Vietnam have led to some rethinking of these calculations. This Note shares their findings and it also provides some pointers that may be useful in estimating the economic benefits of revenue reform projects. Earlier estimates and their shortcomings are closely looked at, as well as customs administration and tax administration. This guidance can also assist in preparation of the technical annex of the financial and economic analysis of individual projects as required by World Bank guidelines.