The underground economy exerts a significant influence on Vietnam's economic landscape, particularly within the financial sector. Given the high level of openness in this sector, it becomes particularly vulnerable to the impact of underground economic activities. Moreover, the existing legal framework that governs the underground economy within Vietnam's financial sector is still incomplete, resulting in legal gaps that underground operators exploit to their advantage. This exploitation has severe repercussions, causing detrimental effects on the economy, and the state budget, and impeding the legitimate rights and interests of numerous citizens. In light of this, it is imperative to adopt a comprehensive array of measures aimed at preventing and addressing underground economic activities in the public financial sector, as well as curbing illicit underground practices related to taxation and fees. These are such important measures that can significantly contribute to the enhancement of laws pertaining to the management of the underground economy within Vietnam's financial sector.