This report analyzes tax policy reforms needed in Timor-Leste to boost domestic revenue mobilization and help drive more inclusive and sustainable economic growth. Timor-Leste, one of Southeast Asia's poorest countries, relies heavily on petroleum income to finance its large public expenditure envelope. As a result, the country remains vulnerable to revenue fluctuations which in turn contribute to macroeconomic volatility. This report concludes that a more diversified approach to domestic resource mobilization will reduce such volatility and provide more stability in government finances. To achieve this, it proposes a modern value-added tax is introduced alongside other tax administration reforms, and that these need to be complemented by more efficient public expenditure.