The paper examines domestic revenue mobilization in Mauritania and proposes strategies to enhance tax revenue collection to address fiscal sustainability challenges and finance critical investment projects. Despite recent progress, Mauritania’s tax-to-GDP ratio remains below that of its peers, constrained by a complex legal framework, numerous derogatory tax regimes, and inefficiencies in revenue administration. The analysis indicates that Mauritania could increase tax revenues by up to 3.4% of GDP in the medium term, thus reducing its tax gap by one-third. Key policy recommendations include reducing VAT exemptions, replacing corporate tax exemptions with cost-based incentives, reforming the personal income tax system, broadening the consumption tax base, simplifying tax procedures, managing tax arrears more effectively, and strengthening tax compliance.