Legal analysis: the file transfer letter will expire and the file transfer letter will be valid for 30 days. There are still some shift letters that do not indicate the validity period, which does not mean that there is no time limit. Even if the validity period is not indicated, the handover procedures should be handled within one month. Class letter is a term of personnel work, which comes from the personnel management system under the highly planned system. Under the highly planned system, there are strict procedures for the flow of human resources, and the file transfer letter is a letter sent by the transfer-in unit to the current unit to retrieve the personal personnel files of the person to be transferred. Often used between state organs and institutions.

Legal basis: Article 55 of the Promotion Law of Rural Revitalization in People's Republic of China (PRC) promotes the formation of a human resources market with equal competition, standardization and order, and the unification of urban and rural areas, and improves the public employment and entrepreneurship service system with equality between urban and rural areas. Local people's governments at or above the county level shall take measures to promote farmers who have stable employment and life in cities and towns to settle in cities voluntarily and orderly, and shall not take the recovery of land contractual management rights, homestead use rights and collective income distribution rights as conditions for farmers to settle in cities and towns; Promote farmers who have obtained residence permits and their accompanying families to enjoy basic urban public services. The state encourages social capital to develop projects linked to farmers' interests in rural areas, and encourages urban residents to travel to rural areas, take vacations, maintain health and provide for the elderly, but it shall not harm the rural ecological environment and the legitimate rights and interests of rural collective economic organizations and their members.