The presence of Afghan nationals in Iran over the past five decades has been accompanied by successive waves of migration. Recent developments in Afghanistan and the return of the Taliban have intensified the massive influx of migrants—predominantly undocumented—and the "Regularization Plan for Foreign Nationals," aimed at identifying, controlling, and deporting them, represents Iran's latest policy in this regard. This study employs the Social Impact Assessment (SIA) method and analyzes documentary, field, and statistical data to provide a balanced evaluation of the plan's potential positive and negative consequences across social, economic, security, and international dimensions. The findings indicate that although the implementation of the plan is associated with positive achievements such as reducing urban crime, alleviating the burden of hidden subsidies, and enhancing the sense of social security, it faces serious challenges at the social and economic levels, including rising xenophobia, the promotion of violence, violations of children's rights, the collapse of low cost employment networks, the weakening of small scale industries, and the potential exacerbation of extremism and human trafficking. At the international level, the policy may also pose challenges to Iran's foreign relations and human rights reputation. Finally, drawing on the SIA approach, a set of preventive, mitigative, and compensatory policies is proposed to manage the negative repercussions while reinforcing the plan's positive achievements, in order to facilitate its humane, effective, and balanced implementation.