Regarding this issue, the Social Insurance of Vietnam responded as follows:

According to Official Letter No. 2023/LDTBXH-BHXH dated June 18, 2012, from the Ministry of Labor - Invalids and Social Affairs, for cases where a decision has been made to receive one-time social insurance benefits but the actual one-time social insurance amount has not been disbursed from the social insurance fund, and the worker requests it, the decision to receive one-time social insurance benefits can be canceled to preserve the period of social insurance contributions or continue participation in social insurance.

Therefore, according to the above regulations, if a worker voluntarily applies for one-time social insurance benefits and the social insurance agency has received and processed the application according to the provisions of the Social Insurance Law regarding policies, documents, procedures, and authority, and the one-time social insurance amount has already been disbursed from the social insurance fund and received by the worker, then the received subsidy cannot be returned to preserve the period of social insurance contributions.